Charging system and charging method for increasing service life of battery of terminal and power adapter thereof

ABSTRACT

A charging system, a charge method, and a power adapter are provided. The charging system includes a battery, a first rectifying circuit, a switch circuit, a transformer, a second rectifying circuit, a sampling circuit, and a control circuit. The control circuit outputs a control signal to the switch circuit, and regulates a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of charging the battery.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national phase application based upon an International Application No. PCT/CN2017/070541, filed on Jan. 7, 2017, which claims priority to International Application No. PCT/CN2016/073679, filed on Feb. 5, 2016, and Chinese Application No. 201610600612.3, filed on Jul. 26, 2016. The entire disclosures of the above applications are incorporated herein by reference.

BACKGROUND

1. Field of Disclosure

The present disclosure relates to a terminal device technology, more particularly, to a charging system for a terminal, a charging method for the terminal, and a power adapter.

2. Description of Related Art

Currently, mobile terminals (such as a smart phone) are increasingly popular with consumers. However, the mobile terminals consume a great amount of power so that they need to be charged frequently.

The mobile terminals are usually charged through power adapters. A power adapter generally includes a primary rectifier circuit, a primary filter circuit, a transformer, a secondary rectifier circuit, a secondary filter circuit, and a control circuit, etc. The power adapter converts input 220V alternating current (AC) power into a stable low-voltage direct current (DC) power (such as 5V) suitable for the mobile terminal, so as to provide power to a power management device and a battery of the mobile terminal, thus charging the mobile terminal.

However, as the power of the power adapters increases, for example, when the power is upgraded from 5 W to a higher power, such as 10 W, 15 W, 25 W etc., more electronic components that can sustain a higher power and realize a higher control of accuracy are needed for complementing each other. This causes size of the power adapters to increase as well as manufacturing difficulty of the adapters to also increase.

In general, current flowing through the power adapter of related art is detected with a current sensing resistor and an operational amplifier. The sensing current becomes greater as power of the power adapter becomes greater. Correspondingly, under the premise that the operational amplifier is not saturated, the dynamic range of the detective current is more limited. However, when the mobile terminal is charged with small current outputted by the power adapter, a wider dynamic range of the operational amplifier by using a smaller current sensing resistor or selecting a lower amplification of the operational amplifier) may result in inaccuracy of detection of the small current because of the characteristic of the operational amplifier, which further affects the application of the power adapter.

SUMMARY

The present application is based on the inventor's knowledge and research on the following issues.

With the power of a power adapter becomes higher, the battery tends to polarize and the resistance tends to become larger when the power adapter charges the battery of the mobile terminal; the battery temperature thus rises to reduce the service life of the battery. As a result, the reliability and safety of the battery are affected.

In addition, when an AC power supplies power, most of the equipment cannot operate by directly using the AC power. The reason is that an AC power, such as 220V/50 Hz mains, outputs power intermittently, and in order not to be “intermittent”, electrolytic capacitors need to be used for energy storage. When the power is at the wave trough, the power supply is maintained stably by continuously relying on the energy storage of electrolytic capacitors. Therefore, when a mobile terminal is charged by an AC power supply through a power adapter, the AC power, such as 220V AC power, provided by the AC power supply is first converted into a stable DC power be supplied to the mobile terminal. However, the power adapter charges the battery of the mobile terminal, thus indirectly supplying power to the mobile terminal. The continuity of power supply can be ensured by the battery. As such, the power adapter does not need to continuously output a stable DC power when charging the battery.

Therefore, one objective of the present disclosure is to provide a charging system for a terminal. With the charging system, voltage with a pulsating waveform outputted by a power adapter is directly applied to a battery of the terminal, thereby miniaturizing the power adapter, lowering the cost of the power adapter, and increasing the lifetime of the battery. Besides, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

Another objective of the present disclosure is to provide a power adapter. Still another objective of the present disclosure is to provide a charging method for a terminal.

In order to achieve at least one of the above objectives, one aspect of the present disclosure provides a charging system. The charging system includes a battery, a first rectifying circuit configured to rectify an alternating current to voltage with a first pulsating waveform, a switch circuit configured to modulate the voltage with the first pulsating waveform according to a control signal, a transformer configured to output voltage with a second pulsating waveform according to the modulated voltage with the first pulsating waveform, a second rectifying circuit configured to rectify the voltage with the second pulsating waveform to voltage with a third pulsating waveform, a first current sampling circuit configured to sample current outputted by the second rectifying circuit to obtain a current sampling value, the first current sampling circuit selectively operable in a first current sampling mode and a second current sampling mode, a mode switch circuit configured to control the first current sampling circuit to switch between the first current sampling mode and the second current sampling mode, and a control circuit coupled to the first current sampling circuit, the mode switch circuit, and the mode switch circuit. The control circuit is configured to output the control signal to the switch circuit, configured to control the mode switch circuit to control the first current sampling circuit operating in the first current sampling mode or the second current sampling mode based on a charging mode, and configured to regulate a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of charging the battery.

According to the embodiment of the present disclosure, the charging system for the terminal controls the power adapter to output the voltage with the third pulsating waveform, and directly applies the voltage with the third pulsating waveform output from the power adapter to the battery in the terminal, so that the fast charging of the battery directly by the output voltage/current that is pulsating can be achieved. A magnitude of the output voltage/current that is pulsating changes periodically. As compared with the disclosures of charging with constant voltage and constant current in the related art, the lithium precipitation phenomenon of the lithium battery can be reduced. The service life of the battery can be improved. In addition, the probability of arcing and the force of the contact at the charging interface can further be reduced to improve the life of the charging interface. It is also advantageous in reducing the polarization effect of the battery, improving the charging speed, reducing the battery heat so as to ensure the safety and reliability when the terminal is charged. Additionally, because the power adapter outputs the voltage with the pulsating waveform, there is no necessity to dispose electrolytic capacitors in the power supply adapter. Not only can the power adapter be simplified and miniaturized, but the cost can also be greatly reduced. Additionally, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

In order to achieve at least one of the above objectives, another aspect of the present disclosure provides a power adapter. The power adapter includes a first rectifying circuit configured to rectify an alternating current to voltage with a first pulsating waveform, a switch circuit configured to modulate the voltage with the first pulsating waveform according to a control signal, a transformer configured to output voltage with a second pulsating waveform according to the modulated voltage with the first pulsating waveform, a second rectifying circuit configured to rectify the voltage with the second pulsating waveform to voltage in a third pulsating waveform, a first charging interface coupled to the second rectifying circuit, a first current sampling circuit configured to sample current outputted by the second rectifying circuit to obtain a current sampling value, the first current sampling circuit selectively operable in a first current sampling mode and a second current sampling mode, a mode switch circuit configured to control the first current sampling circuit to switch between the first current sampling mode and the second current sampling mode, and a control circuit coupled to the first current sampling circuit, the mode switch circuit, and the mode switch circuit. The control circuit is configured to output the control signal to the switch circuit, configured to control the mode switch circuit to control the first current sampling circuit operating in the first current sampling mode or the second current sampling mode based on a charging mode, and configured to regulate a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of charging. The first charging interface is configured to apply the voltage with the third pulsating waveform to a battery of a terminal through a second charging interface of the terminal when the second charging interface of the terminal couples to the first charging interface. The battery is coupled to the second charging interface.

According to the embodiment of the present disclosure, the power adapter outputs the voltage with the third pulsating waveform through the first charging interface, and directly applies the voltage with the third pulsating waveform output from the power adapter to the battery through the second charging interface in the terminal, so that the fast charging of the battery directly by the output voltage/current that is pulsating can be achieved. A magnitude of the output voltage/current that is pulsating changes periodically. As compared with the disclosures of charging with constant voltage and constant current in the related art, the lithium precipitation phenomenon of the lithium battery can be reduced. The service life of the battery can be improved. In addition, the probability of arcing and the force of the contact at the charging interface can further be reduced to improve the life of the charging interface. It is also advantageous in reducing the polarization effect of the battery, improving the charging speed, reducing the battery heat so as to ensure the safety and reliability when the terminal is charged. Additionally, because the power adapter outputs the voltage with the pulsating waveform, there is no necessity to dispose electrolytic capacitors in the power supply adapter. Not only can the power adapter simplified and miniaturized, but the cost can also be greatly reduced. Additionally, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

In order to achieve at least one of the above objectives, still another aspect of the present disclosure provides a charging method for a terminal. The charging method for the terminal includes the following acts. An alternating current is rectified to output voltage with a first pulsating waveform when a first charging interface of a power adapter couples a second charging interface of the terminal. The voltage with the first pulsating waveform is modulated by controlling a mode switch circuit. The modulated voltage with the first pulsating waveform is converted into voltage with a second pulsating waveform by a transformer. The voltage with the second pulsating waveform is rectified to output voltage in a third pulsating waveform. The voltage with the third pulsating waveform is applied to a battery of the terminal through the second charging interface. Current corresponding to the voltage with the third pulsating waveform is sampled to obtain a current sampling value, where the first current sampling circuit is selectively operable in a first current sampling mode and a second current sampling mode. The first current sampling circuit is controlled to operate in the first current sampling mode or the second current sampling mode according to a charging mode, and regulating a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of charging.

According to the charging method provided in the embodiment of the present disclosure, the voltage with the third pulsating waveform is outputted by controlling the power adapter, and the voltage with the third pulsating waveform output from the power adapter is directly applied to the battery of the terminal, so that the fast charging of the battery directly by the output voltage/current that is pulsating can be achieved. A magnitude of the output voltage/current that is pulsating changes periodically. As compared with the disclosures of charging with constant voltage and constant current in the related art, the lithium precipitation phenomenon of the lithium battery can be reduced. The service life of the battery can be improved. In addition, the probability of arcing and the force of the contact at the charging interface can further be reduced to improve the life of the charging interface. It is also advantageous in reducing the polarization effect of the battery, improving the charging speed, reducing the battery heat so as to ensure the safety and reliability when the terminal is charged. Additionally, because the power adapter outputs the voltage with the pulsating waveform, there is no necessity to dispose electrolytic capacitors in the power supply adapter. Not only can the power adapter simplified and miniaturized, but the cost can also be greatly reduced. Additionally, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a block schematic diagram of a charging system for a terminal that adopts a flyback switching power supply according to one embodiment of the present disclosure.

FIG. 1B illustrates a block schematic diagram of a charging system for a terminal that adopts a forward switching power supply according to one embodiment of the present disclosure.

FIG. 1C illustrates a block schematic diagram of a charging system for a terminal that adopts a push pull switching power supply according to one embodiment of the present disclosure.

FIG. 1D illustrates a block schematic diagram of a charging system for a terminal that adopts a half-bridge switching power supply according to one embodiment of the present disclosure.

FIG. 1E illustrates a block schematic diagram of a charging system for a terminal that adopts a full-bridge switching power supply according to one embodiment of the present disclosure.

FIG. 2A illustrates a block schematic diagram of a charging system for a terminal according to one embodiment of the present disclosure.

FIG. 2B illustrates a circuit diagram of a first current sampling circuit according to another embodiment of the present disclosure.

FIG. 3 illustrates a waveform of a charging voltage output to a battery from a power adapter according to one embodiment of the present disclosure.

FIG. 4 illustrates a waveform of a charging current output to a battery from a power adapter according to one embodiment of the present disclosure.

FIG. 5 illustrates a waveform of a control signal output to a switch circuit according to one embodiment of the present disclosure.

FIG. 6 illustrates a schematic diagram of a fast charging process according to one embodiment of the present disclosure.

FIG. 7A illustrates a block schematic diagram of a charging system for a terminal according to one embodiment of the present disclosure.

FIG. 7B illustrates a block schematic diagram of a power adapter having an LC filter circuit according to one embodiment of the present disclosure.

FIG. 8 illustrates a block schematic diagram of a charging system for a terminal according to another embodiment of the present disclosure.

FIG. 9 illustrates a block schematic diagram of a charging system for a terminal according to still another embodiment of the present disclosure.

FIG. 10 illustrates a block schematic diagram of a charging system for a terminal according to yet another embodiment of the present disclosure.

FIG. 11 illustrates a block schematic diagram of a sampling circuit according to one embodiment of the present disclosure.

FIG. 12 illustrates a block schematic diagram of a charging system for a terminal according to an additional embodiment of the present disclosure.

FIG. 13 illustrates a block schematic diagram of a terminal according to one embodiment of the present disclosure.

FIG. 14 illustrates a block schematic diagram of a terminal according to another embodiment of the present disclosure.

FIG. 15 illustrates a flowchart of a charging method for a terminal according to one embodiment of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present application are illustrated in detail in the accompanying drawings, in which like or similar reference numerals refer to like or similar elements or elements having the same or similar functions throughout the specification. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be illustrative of the present application, and are not to be construed as limiting the scope of the present application.

Before a charging system and a charging method for a terminal and a power adapter according to the embodiments of the present disclosure are provided, description of a power adapter for charging a chargeable device (e.g. a terminal), that is, an “associated adapter” as called in the following, in the relevant technology is first described.

The associated adapter constantly maintains an output voltage when the associated adapter operates in a constant voltage mode, such as 5V, 9V, 12V, or 20V, etc.

Voltage output from the associated adapter is not suitable to be directly applied to two terminals of a battery, rather, the voltage output from the associated adapter needs to be first converted through a converter circuit in a chargeable device (such as a terminal) so as to obtain an expected charging voltage and/or a charging current by a battery in the chargeable device (such as a terminal).

The converter circuit is configured to convert the voltage output from the associated adapter so as to satisfy the expected requirement of the charging voltage and/or the charging current by the battery.

As an example, the converter circuit may refer to a charging management module, such as a charging IC in the terminal, which is configured to manage the charging voltage and/or the charging circuit of the battery during the charging process of the battery. The converter circuit has a function of a voltage feedback module and/or a function of a current feedback module to manage the charging voltage and/or the charging circuit of the battery.

For example, the charging process of the battery may include at least one of a trickle charging stage, a constant current charging stage, and a constant voltage charging stage. During the trickle charging stage, the converter circuit can utilize a current feedback loop so that a current entering into the battery satisfies a magnitude of the charging current expected by the battery (such as a first charging current) in the trickle charging stage. During the constant current charging stage, the converter circuit can utilize the current feedback loop so that the current entering into the battery satisfies magnitude of the charging current expected by the battery (such as a second charging current, the second charging current may be greater than the first charging current) in the constant current charging stage. During the constant voltage charging stage, the converter circuit can utilize a voltage feedback loop so that voltage applied to the two terminals of the battery satisfies a magnitude of the charging voltage expected by the battery in the constant voltage charging stage.

As an example, when the voltage output from the associated adapter is greater than the charging voltage expected by the battery, the converter circuit can be configured to step down the voltage output from the associated adapter so that the charging voltage obtained after buck conversion satisfies the charging voltage expected by the battery. As another example, when the voltage output from the associated adapter is less than the charging voltage expected by the battery, the converter circuit can be configured to boost the voltage output from the associated adapter so that the charging voltage obtained after the boost conversion satisfies the charging voltage expected by the battery.

In yet another example, a constant 5V voltage output from the associated adapter is taken as an example. When the battery includes a single cell (take a lithium battery cell for example, a charging cut-off voltage of a single cell is 4.2V), the converter circuit (such as a buck circuit) can step down the voltage output from the associated adapter so that the charging voltage obtained after bucking satisfies the charging voltage expected by the battery.

In yet another example, the constant voltage of 5V output from the associated adapter is taken as an example. When the battery is a battery having two or more than two single cells (take the lithium battery cell for example, the charging cut-off voltage of the single cell is 4.2V) connected in series, the converter circuit (such as a boost circuit) can boost the voltage output from the associated adapter so that the charging voltage obtained after boosting satisfies the charging voltage expected by the battery.

Because the converter circuit is limited by low conversion efficiency of the circuit, electrical energy that is not converted, is dissipated in a form of heat. This heat will accumulate inside the chargeable device (such as the terminal), where a design space and a heat dissipation space of the chargeable device (such as the terminal) are both limited (for example, a physical size of a mobile terminal used by a user becomes increasingly thin and light, and a great number of electronic components are closely arranged inside the mobile terminal to enhance performance of the mobile terminal). Not only does it create increased difficulty of designing the converter circuit, but also it is very difficult to dissipate heat accumulated inside the chargeable device (such as the terminal) in a timely manner, thus causing the chargeable device (such as the terminal) to become abnormal.

For example, heat accumulated by the converter circuit is likely to cause thermal interference with electronic components near the converter circuit so that the electronic components work abnormally; and/or, for example, the heat accumulated on the converter circuit is likely to shorten service lives of the converter circuit and the electronic components nearby; and/or, for example, the heat accumulated on the converter circuit is likely to cause thermal interference with the battery so that the battery charges and discharges abnormally; and/or, for example, the heat accumulated on the converter circuit is likely to raise temperature of the chargeable device (such as the terminal) so that the user experience is affected when the user charges; and/or, for example, the heat accumulated on the converter circuit is likely to cause a short circuit of the converter circuit itself so that the battery charges abnormally when the voltage output from the associated adapter is directly applied to the two terminals of a battery. Under the circumstances that the battery is over charged for a long time, the battery can even explode, which in turn causes a certain security concern.

A power adapter according to the embodiment of the present disclosure can acquire battery state information. The battery state information at least includes a current battery level information and/or voltage information. The power adapter adjusts an output voltage of the power adapter itself based on the acquired battery state information to satisfy a charging voltage and/or a charging current expected by the battery. Voltage outputted by the power adapter after adjustment can be directly applied to two terminals of the battery to charge the battery. In some embodiments, an output of the power adapter may be voltage with a pulsating waveform.

The power adapter has functions of a voltage feedback module and a current feedback module, to achieve the management of the charging voltage and/or the charging circuit of the battery.

The power adapter adjusting the output voltage of the power adapter itself based on the acquired battery state information may refer to the power adapter can acquire the battery state information in a real-time manner and adjust the voltage output from the power adapter itself based on real-time state information of the battery acquired every time, to satisfy the charging voltage and/or the charging current expected by the battery.

The power adapter adjusting the output voltage of the power adapter itself based on the battery state information acquired in a real-time manner may refer to the power adapter can acquire current state information of the battery at different times during a charging process as the charging voltage of the battery continues to rise during the charging process, and adjust the output voltage of the power adapter itself based on the current state information of the battery in a real-time manner to satisfy the charging voltage and/or the charging current expected by the battery. The voltage output from the power adapter after adjustment can be directly applied to the two terminals of the battery to charge the battery.

For example, the charging process of the battery may include at least one of a trickle charging stage, a constant current charging stage, and a constant voltage charging stage. During the trickle charging stage, the power adapter can output a first charging current to charge the battery so as to satisfy the charging current expected by the battery (in some embodiments, the first charging current may be current with a pulsating waveform). During the constant current charging stage, the power adapter can utilize a current feedback loop so that a current output from the power adapter and enters into the battery satisfies the charging current expected by the battery (for example, a second charging current, the second charging current may similarly be a current with a pulsating waveform, the second charging current may be greater than the first charging current, a peak value of the current with the pulsating waveform of the constant current charging stage may be greater than a peak value of the current with the pulsating waveform of the trickle charging stage, and a constant current of the constant current charging stage may refer to the peak value or an average value of the current with the pulsating waveform basically remaining unchanged). During the constant voltage charging stage, the power adapter can utilize a voltage feedback loop so that voltage (that is, the voltage with the pulsating waveform) outputted from the power adapter to a piece of chargeable device (such as a terminal) in the constant voltage charging stage is maintained constantly.

For example, the power adapter according to the embodiment of the present disclosure can be mainly configured to control the constant current charging stage of the battery in the chargeable device (such as the terminal). In other embodiments, functions of controlling the trickle charging stage and the constant voltage charging stage of the battery in the chargeable device (such as the terminal) may be cooperatively achieved by the power adapter according to the embodiment of the present disclosure and an additional charging chip in the chargeable device (such as the terminal). When compared with the constant current charging stage, charging power received by the battery in the trickle charging stage and the constant voltage charging stage is less, the efficiency conversion loss and heat accumulation of the charging chip in the chargeable device (such as the terminal) are thus acceptable. It is noted that the constant current charging stage or the constant current stage according to the embodiment of the present disclosure may refer to the charging mode that controls an output current of the associated adapter and does not require that the output current of the power adapter to be maintained completely unchanged, for example, may refer to that the peak value or the average value of the current with the pulsating waveform output from the associated adapter basically remains unchanged or basically remains unchanged within a period of time. For example, in practice, the power adapter in the constant current charging stage usually uses a multi-stage constant current charging method to charge.

The multi-stage constant current charging may have N constant current stages (N is a positive integer not less than 2). The multi-stage constant current charging uses a predetermined charging current to start a first charging stage. The N constant current stages of the multi-stage constant current charging are sequentially executed from the first stage to the (N−1)th stage. After a previous constant current stage is changed to a next constant current stage in the constant current stages, the peak value or the average value of the current with the pulsating waveform can become smaller. When a battery voltage reaches a threshold voltage value for terminating charging, the previous constant current stage will change to the next constant current stage in the constant current stages. The current conversion process between two adjacent constant current stages may be gradual, or may be a stepped jump.

In addition, it is noted that the term “terminal” as used in the embodiments of the present disclosure may include, but is not limited to, a device configured to be connected via a wired connection (for example, via a public switched telephone network (PSTN), a digital subscriber line (DSL), a digital cable, a direct cable connection, and/or another data connection/network) and/or a device configured to receive/send a communication signal via a wireless interface (such as a cellular network, a wireless local area network (WLAN), a digital television network such as a DVB-H network, a satellite network, an AM-FM broadcast transmitter, and/or another communication terminal). A terminal configured to communicate via a wireless interface may be referred to as a “wireless communication terminal”, a “wireless terminal”, and/or a “mobile terminal”. Examples of mobile terminal include, but are not limited to, a satellite or cell phone; a personal communication system (PCS) terminal that can combine a cellular radiotelephone, data processing, facsimile, and data communications capabilities; may include a radiotelephone, a pager, an Internet/Intranet access, a Web browser, an electronic organizer, a calendar, and/or a personal digital assistant (PDA) equipped with a global positioning System (GPS) receiver; and a common laptop and/or palm type receiver or some other electronic devices including a transmitter-receiver radiotelephone.

In addition, according to the embodiment of the present disclosure, when the voltage with the pulsating waveform output from the power adapter is directly applied to the battery of the terminal so as to charge the battery, the charging current is characterized by a pulsating wave, such as a clipped sine wave, and it is understood that the charging current charges the battery in an intermittent manner. A period of the charging current changes depending on an input AC power, such as a frequency of an AC grid. For example, a frequency corresponding to the period of the charging current is an integer multiple or a reciprocal of the frequency of the AC grid. Additionally, the charging current charges the battery in an intermittent manner. A current waveform corresponding to the charging current may be composed of one pulse or one group of pulses synchronized with the grid.

A description of a charging system for a terminal and a power adapter and a charging method for a terminal according to the embodiment of the present disclosure is provided as follows with reference to the figures.

A description is provided with reference to FIG. 1A to FIG. 14. A charging system for a terminal according to the embodiment of the present disclosure includes a power adapter 1 and a terminal 2.

As shown in FIG. 2A and FIG. 2B, the power adapter 1 includes a first rectifying circuit 101, a switch circuit 102, a transformer 103, a second rectifying circuit 104, a first charging interface 105, a first current sampling circuit 1061, a mode switch circuit 115 and a control circuit 107. The first rectifying circuit 101 rectifies an input AC power (mains, such as AC220V) to output voltage in a first pulsation waveform, such as a voltage in a clipped pulsating waveform. As shown in FIG. 1A, the first rectifying circuit 101 may be a full bridge rectifier circuit constituted by four diodes. The switch circuit 102 is configured to modulate the voltage with the first pulsating waveform based on a control signal. The switch circuit 102 may be constituted by a metal-oxide-semiconductor (MOS) transistor, and perform a peak clipping modulation to the voltage in the clipped pulsating waveform through performing a pulse width modulation (PWM) control to the transistor. The transformer 103 is configured to output voltage with a second pulsating form based on the voltage with the first pulsating form thus modulated. The second rectifying circuit 104 is configured to rectify the voltage with the second pulsating waveform to output voltage in a third pulsating form. The second rectifying circuit 104 may be constituted by a diode or a MOS transistor, which can achieve secondary synchronous rectification so that the third pulsating waveform is synchronized with the modulated first pulsating waveform. It is noted that the third pulsating waveform being synchronized with the modulated first pulsating waveform refers to that a phase of the third pulsating waveform and a phase of the modulated first pulsating waveform are consistent, and a change trend of an amplitude of the third pulsating waveform and a change trend of an amplitude of the modulated first pulsating waveform are consistent. The first charging interface 105 and the second rectifying circuit 104 are connected. The first current sampling circuit 1061 is configured to sample current outputted by the second rectifying circuit 104 to obtain a current sampling value. The first current sampling circuit 1061 is selectively operable in a first current sampling mode and a second current sampling mode. The mode switch circuit 115 is configured to control the first current sampling circuit 1061 to switch between the first current sampling mode and the second current sampling mode. The control circuit 107 is coupled to the first current sampling circuit 1061, the mode switch circuit 115, and the switch circuit 102. The control circuit 107 is configured to output the control signal to the switch circuit 102 to control the mode switch circuit 115 to control the first current sampling circuit 1061 operating in the first current sampling mode or the second current sampling mode based on a charging mode, and configured to regulate a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of charging.

As shown in FIG. 2A, the terminal 2 includes a second charging interface 201 and a battery 202. The second charging interface 201 is connected to the battery 202. When the second charging interface 201 and the first charging interface 105 are connected, the second charging interface 201 applies the voltage with the third pulsating waveform to the battery 202 to achieve to charging of the battery 202.

In one embodiment of the present disclosure, as shown in FIG. 1A, the power adapter 1 may adopt a flyback switching power supply. In greater detail, the transformer 103 includes a primary winding and a secondary winding. One terminal of the primary winding is connected to a first output terminal of the first rectifying circuit 101. A second output terminal of the first rectifying circuit 101 is grounded. Another terminal of the primary winding is connected to the switch circuit 102 (for example, the switch circuit 102 is the MOS transistor, so the another terminal of the primary winding is connected to a drain of the MOS transistor). The transformer 103 is configured to output the voltage with the second pulsating waveform based on the modulated voltage with the first pulsating waveform.

The transformer 103 is a high-frequency transformer, which may have an operating frequency of 50 KHz to 2 MHz. The modulated voltage with the first pulsating waveform is coupled to a secondary side by the high-frequency transformer and is output by the secondary winding. According to the embodiment of the present disclosure, using the high-frequency transformer can take advantage of the feature of smaller size of the high-frequency transformer as compared with a low-frequency transformer (a low-frequency transformer is also called a power frequency transformer, which is mainly used for the mains frequency, such as 50 Hz or 60 Hz AC)), thus achieving the miniaturization of the power adapter 1.

According to one embodiment of the present disclosure, as shown in FIG. 1B, the power adapter 1 may adopt a forward switching power supply. In greater detail, the transformer 103 includes a first winding, a second winding, and a third winding. A dotted terminal of the first winding is connected to a second output terminal of the first rectifying circuit 101 through a backward diode. A non-dotted terminal of the first winding is first connected to a dotted terminal of the second winding and then they are connected to a first output terminal of the first rectifying circuit 101. A non-dotted terminal of the second winding is connected to the switch circuit 102. The third winding and the second rectifying circuit 104 are connected. The backward diode has the effect of reverse clipping. An induced electromotive force generated by the first winding can limit an amplitude of a counter electromotive force through the backward diode, and energy caused by amplitude limitation is returned to an output of the first rectifying circuit 101 to charge the output of the first rectifying circuit 101. In addition, a magnetic field generated by a current passing the first winding can demagnetize a core of the transformer so that a magnetic field strength in a transformer core is restored to an initial state. The transformer 103 is configured to output the voltage with the second pulsating waveform based on the modulated voltage with the first pulsating waveform.

According to one embodiment of the present disclosure, as shown in FIG. 1C, the power adapter may adopt a push-pull switching power supply. In greater detail, the transformer 103 includes a first winding, a second winding, a third winding, and a fourth winding. A dotted terminal of the first winding is connected to the switch circuit 102. A non-dotted terminal of the first winding is first connected to a dotted terminal of the second winding and then they are connected to a first output terminal of the first rectifying circuit 101. A non-dotted terminal of the second wining is connected to the switch circuit 102. A non-dotted terminal of the third winding is connected to a dotted terminal of the fourth winding. The transformer 103 is configured to output the voltage with the second pulsating waveform based on the modulated voltage with the first pulsating waveform.

As shown in FIG. 1C, the switch circuit 102 includes a first MOS transistor Q1 and a second MOS transistor Q2. The transformer 103 includes the first winding, the second winding, the third winding, and the fourth winding. The dotted terminal of the first winding is connected to a drain of the first MOS transistor Q1 in the switch circuit 102. The non-dotted terminal of the first winding is connected to the dotted terminal of the second winding, and a node between the non-dotted terminal of the first winding and the dotted terminal of the second winding is connected to the first output terminal of the first rectifying circuit 101. The non-dotted terminal of the second wining is connected to a drain of the second MOS transistor Q2 in the switch circuit 102. A source of the first MOS transistor Q1 is first connected to a source of the second MOS transistor Q2 and then they are connected to a second output terminal of the first rectifying circuit 101. A dotted terminal of the third winding is connected to a first input terminal of the second rectifying circuit 104. The non-dotted terminal of the third winding is connected to the dotted terminal of the fourth winding, and a node between the non-dotted terminal of the third winding and the dotted terminal of the fourth winding is grounded. A non-dotted terminal of the fourth winding is connected to a second input terminal of the second rectifying circuit 104.

As shown in FIG. 1C, the first input terminal of the second rectifying circuit 104 is connected to the dotted terminal of the third winding. The second input terminal of the second rectifying circuit 104 is connected to the non-dotted terminal of the fourth winding. The second rectifying circuit 104 is configured rectify the voltage with the second pulsating waveform to output the voltage with the third pulsating waveform. The second rectifying circuit 104 may include two diodes. An anode of one diode is connected to the dotted terminal of the third winding. An anode of the other diode is connected to the non-dotted terminal of the fourth winding. Cathodes of the two diodes are connected together.

According to one embodiment of the present disclosure, as shown in FIG. 1D, the power adapter 1 may adopt a half-bridge switching power supply. In greater detail, the switch circuit 102 includes a first MOS transistor Q1, a second MOS transistor Q2, a first capacitor C1, and a second capacitor C2. The first capacitor C1 and the second capacitor C2 are first connected in series and then they are connected in parallel with output terminals of the first rectifying circuit 101. The first MOS transistor Q1 and the second MOS transistor Q2 are first connected in series and then they are connected in parallel with the output terminals of the first rectifying circuit 101. The transformer 103 includes a first winding, a second winding, and a third winding. A dotted terminal of the first winding is connected to a node between the first capacitor C1 and the second capacitor C2 connected in series. A non-dotted terminal of the first winding is connected to a node between the first MOS transistor Q1 and the second MOS transistor Q2 connected in series. A dotted end of the second winding is connected to a first input terminal of the second rectifying circuit 104. A non-dotted terminal of the second winding is first connected to a dotted terminal of the third winding and then they are grounded. A non-dotted terminal of the third winding is connected to a second input terminal of the second rectifying circuit 104. The transformer 103 is configured to output the voltage with the second pulsating waveform based on the modulated voltage with the first pulsating waveform.

According to one embodiment of the present disclosure, as shown in FIG. 1E, the power adapter 1 may adopt a full-bridge switching power supply. In greater detail, the switch circuit 102 includes a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, and a fourth MOS transistor Q4. The third MOS transistor Q3 and the fourth MOS transistor Q4 are first connected in series and then they are connected in parallel with output terminals of the first rectifying circuit 101. The first MOS transistor Q1 and the second MOS transistor Q2 are first connected in series and then they are connected in parallel with the output terminals of the first rectifying circuit 101. The transformer 103 includes a first winding, a second winding, and a third winding. A dotted terminal of the first winding is connected to a node between third MOS transistor Q3 and the fourth MOS transistor Q4 connected in series. A non-dotted terminal of the first winding is connected to a node between first MOS transistor Q1 and the second MOS transistor Q2 connected in series. A dotted terminal of the second winding is connected to a first input terminal of the second rectifying circuit 104. A non-dotted terminal of the second winding is first connected to a dotted terminal of the third winding and then they are grounded. A non-dotted terminal of the third winding is connected to a second input terminal of the second rectifying circuit 104. The transformer 103 is configured to output the voltage with the second pulsating waveform based on the modulated voltage with the first pulsating waveform.

Therefore, the power adapter 1 can use any of the flyback switching power supply, the forward switching power supply, the push pull switching power supply, the half-bridge switching power supply, and the full-bridge switching power supply to output the voltage with the pulsating waveform according to embodiments of the present disclosure.

In addition to that, as shown in FIG. 1A, the second rectifying circuit 104 is connected to the secondary winding of the transformer 103. The second rectifying circuit 104 is configured to rectify the voltage with the second pulsating waveform to output the voltage in a third pulsating form. The second rectifying circuit 104 may be constituted by the diode to achieve secondary synchronous rectification so that the third pulsating waveform is synchronized with the modulated first pulsating waveform. It is noted that the third pulsating waveform being synchronized with the modulated first pulsating waveform refers to that the phase of the third pulsating waveform and the phase of the modulated first pulsating waveform are consistent, and the change trend of the amplitude of the third pulsating waveform and the change trend of the amplitude of the modulated first pulsating waveform are consistent. The first charging interface 105 and the second rectifying circuit 104 are connected. The sampling circuit 106 includes a first current sampling circuit 1061 and a first voltage sampling circuit 1062. The sampling circuit 106 is configured to sample the voltage and/or the current output from the second rectifying circuit 104 to obtain the voltage sampling value and/or the current sampling value. The control circuit 107 is connected to the sampling circuit 106 and the switch circuit 102. The control circuit 107 outputs the control signal to the switch circuit 102, and modulates the duty cycle of the control signal based on the voltage sampling value and/or the current sampling value so that the voltage with the third pulsating waveform output from the second rectifying circuit 104 satisfies the charging requirement.

As shown in FIG. 1A, the terminal 2 includes the second charging interface 201 and the battery 202. The second charging interface 201 is connected to the battery 202. When the second charging interface 201 and the first charging interface 105 are connected, the second charging interface 201 applies the voltage with the third pulsating waveform to the battery 202 to achieve to charging of the battery 202.

The voltage with the third pulsating waveform satisfying the charging requirement refers to that the voltage and a current with the third pulsating waveform satisfy the charging voltage and the charging current when the battery is charged. That is, the control circuit 107 modulates the duty cycle of the control signal, such as a PWM signal, based on voltage and/or a current output from the power adapter thus sampled to adjust an output of the second rectifying circuit 104 in a real-time manner. A closed-loop regulation control is thus realized so that the voltage in the third pulsation waveform satisfies the charging requirement of the terminal 2 to ensure that the battery 202 is safely and reliably charged. A charging voltage waveform output to the battery 202 being regulated through the duty cycle of the PWM signal is shown in FIG. 3. A charging current waveform output to the battery 202 being regulated through the duty cycle of the PWM signal is shown in FIG. 4.

When modulating the duty cycle of the PWM signal, a regulating instruction can be generated based on the voltage sampling value, or the current sampling value, or the voltage sampling value and the current sampling value.

Hence, according to the embodiment of the present disclosure, the voltage in the first pulsation waveform, that is, the voltage in the clipped pulsating waveform, which is rectified is directly modulated by performing PWM peak clipping through controlling the switch circuit 102, and delivered to the high-frequency transformer to be coupled from the primary side to the secondary side through the high-frequency transformer, and then be recovered as the voltage/a current in the clipped pulsating waveform through synchronous rectification to be directly delivered to the battery so as to achieve the fast charging of the battery. An amplitude of the voltage in the clipped pulsating waveform can be regulated through modulating the duty cycle of the PWM signal. As a result, the output of the power adapter satisfies the charging requirement of the battery. It can be seen that the power adapter according to the embodiment of the present disclosure removes the electrolytic capacitors on the primary side and the secondary side. Through using the voltage in the clipped pulsating waveform to directly charge the battery, the size of the power adapter can be reduced to miniaturize the power adapter and significantly reduce the cost.

In one embodiment of the present disclosure, the control circuit 107 may be a micro controller unit (MCU). That is, the control circuit 107 may be a microprocessor integrated with a switch-driven control function, a synchronous rectification function, and a voltage and current regulation control function.

According to one embodiment of the present disclosure, the control circuit 107 is further configured to modulate a frequency of the control signal based on the voltage sampling value and/or the current sampling value. The PWM signal output to the switch circuit 102 can thus be controlled to be continuously output for a period of time and then be stopped. After the output has been stopped for a predetermined time, the output of the PWM is turned on again. In this manner, the voltage applied to the battery is intermittent and the battery is intermittently charged. As a result, the security worry caused by serious heating when the battery is continuously charged can be avoided to improve the reliability and safety of battery charging.

For a lithium battery, in the low temperature condition, the polarization tends to be intensified during the charging process owing the decline of the conductive abilities of the ions and electrons of the lithium battery itself. The continuous charging method will make this polarization become even more obvious, and at the same time increase the possibility of lithium precipitation, thus affecting the safe performance of the battery. In addition, the continuous charging will result in continuous accumulation of heat caused by charging, the interior temperature of the battery also continuously rises. When the temperature exceeds a certain limit value, the battery performance will be limited and at the same time the security worry is increased.

According to the embodiment of the present disclosure, through modulating the frequency of the control signal, the power adapter outputs in an intermittent manner. This situation is equivalent to that the stationary process of the battery is introduced during the battery charging process, which can alleviate the possible lithium precipitation phenomenon caused by polarization in continuous charging and reduce the effect caused by continuous accumulation of heat. The temperature is thus decreased to ensure the reliability and safety of the battery charging.

The control signal output to the switch circuit 102 may be shown in FIG. 5. The PWM signal is first continuously output for a period of time and then is stopped for a period of time, and then is continuously output for a period of time. As a result, the control signal output to the switch circuit 102 is intermittent and the frequency is adjustable.

As shown in FIG. 1A, the control circuit 107 is connected to the first charging interface 105. The control circuit 107 is further configured to communicate with the terminal 2 through the first charging interface 105 to acquire state information of the terminal 2. In this manner, the control circuit 107 is further configured to modulate the duty cycle of the control signal, such as the PWM signal, based on the state information of the terminal 2, and/or the voltage sampling value and/or the current sampling value.

The state information of the terminal 2 may include a battery level, a battery temperature, the battery voltage, interface information of the terminal, or path impedance information of the terminal, etc.

In greater detail, the first charging interface 105 includes power lines and data lines. The power lines are configured to charge the battery. The data lines are configured to communicate with the terminal 2. When the second charging interface 201 is connected to the first charging interface 105, the power adapter 1 and the terminal 2 can send a communication inquiry instruction to each other, and establish a communication connection between the power adapter 1 and the terminal 2 after receiving a reply instruction correspondingly. The control circuit 107 can acquire the state information of the terminal 2 so as to negotiate a charging mode and the charging parameters (such as the charging current, the charging voltage) with the terminal 2 and control the charging process.

The charging mode supported by the power adapter and/or the terminal may include a second charging mode and a first charging mode. A charge rate of the first charging mode is greater than a charge rate of the second charging mode (for example, a charging current of the first charging mode is greater than a charging current of the second charging mode). Generally speaking, the second charging mode can be understood as the charging mode in which the rated output voltage is 5V and the rated output current is less than or equal to 2.5A. In addition, in the second charging mode, D+ and D− in the data lines in an output port of the power adapter may be short circuited. However, the first charging mode according to the embodiment of the present disclosure is different. In the first charging mode of the embodiment of the present disclosure, the power adapter can communicate with the terminal by utilizing D+ and D− in the data lines to achieve data exchange, that is, the power adapter and the terminal can send a fast charging instruction to each other. The power adapter sends a fast charging inquiry instruction to the terminal. The power adapter acquires the state information of the terminal based on a reply instruction of the terminal after receiving a fast charging reply instruction of the terminal to enable the first charging mode. In the first charging mode, the charging current can be greater than 2.5A, for example, can be up to 4.5A or even greater. However, the second charging mode according to the embodiment of the present disclosure is not limited. As long as the power adapter supports two charging modes, and a charge rate (or current) of one of the charging modes is greater than a charge rate of the other charging mode, the charging mode having the slower charge rate can be understood as the second charging mode. Regarding the charging power, the charging power corresponding to the first charging mode can be greater than or equal to 15 W.

The control circuit 107 communicates with the terminal 2 through the first charging interface 105 to determine the charging mode. The charging mode includes the first charging mode and the second charging mode.

In greater detail, the power adapter and the terminal are connected through a universal serial bus (USB) interface. The USB interface may be a normal USB interface, a micro USB interface, or other type USB interfaces. Data lines in the USB interface are the data lines in the first charging interface and are configured to provide a bidirectional communication between the power adapter and the terminal. The data lines may be a D+ line and/or a D− line in the USB interface, and the bidirectional communication can refer to the information exchange between the power adapter and the terminal.

The power adapter performs the bidirectional communication with the terminal through the data lines in the USB interface to determine that the terminal is charged by the first charging mode.

It is noted that during the process that the power adapter negotiates with the terminal to determine whether or not the terminal is charged by the first charging mode, the power adapter may only be connected to the terminal and does not charge the terminal, or may charge the terminal by the second charging mode, or may use a small current to charge the terminal. The embodiment of the present disclosure is not limited in this regard.

The power adapter adjusts the charging current to a charging current corresponding to the first charging mode so as to charge the terminal. After determining to use the first charging mode to charge the terminal, the power adapter can directly adjust the charging current to the charging current corresponding to the first charging mode, or can negotiate with the terminal to determine the charging current of the first charging mode. For example, the charging current corresponding to the first charging mode is determined based on a current power level of the battery in the terminal.

According to the embodiment of the present disclosure, the power adapter does not blindly increase the output current to perform fast charging. Rather, the power adapter needs to perform the bidirectional communication with the terminal so as to negotiate whether the first charging mode can be used or not. As compared with the prior art, the safety of fast charging process is increased.

Optionally, to serve as one embodiment, when the control circuit performs the bidirectional communication with terminal through the data lines in the first charging interface to determine that the terminal is charged by the first charging mode, the control circuit sends a first instruction to the terminal. The first instruction is configured to inquire of the terminal whether to enable the first charging mode or not. The control circuit receives a reply instruction responsive to the first instruction from the terminal. The reply instruction responsive to the first instruction is configured to indicate that the terminal agrees to enable the first charging mode.

Optionally, to serve as one embodiment, before the control circuit sends the first instruction to the terminal, the power adapter charges the terminal under the second charging mode, and the control circuit sends the first instruction to the terminal after determining that a charging time of the second charging mode is longer than a predetermined threshold value.

After the power adapter determines that the charging time of the second charging mode is longer than the predetermined threshold value, the power adapter can assume that the terminal has identified itself as a power adapter and can enable a fast charging inquiry communication.

Optionally, to serve as one embodiment, after the power adapter determines to use a charging current greater than or equal to a predetermined threshold current value to charge for a predetermined time, the power adapter sends the first instruction to the terminal.

Optionally, to serve as one embodiment, the control circuit is further configured to control the power adapter through controlling the switch circuit so as to adjust the charging current to the charging current corresponding to the first charging mode. In addition, the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface before the power adapter uses the charging current corresponding to the first charging mode to charge the terminal so as to determine a charging voltage corresponding to the first charging mode and control the power adapter to adjust the charging voltage to the charging voltage corresponding to the first charging mode.

Optionally, to serve as one embodiment, when the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine the charging voltage corresponding to the first charging mode, the control circuit sends a second instruction to the terminal. The second instruction is configured to inquire whether or not a current output voltage of the power adapter is suitable as a charging voltage of the first charging mode. The control circuit receives a reply instruction responsive to the second instruction sent by the terminal. The reply instruction responsive to the second instruction is configured to indicate that the current output voltage of the power adapter is suitable, excessively high, or excessively low. The control circuit determines the charging voltage of the first charging mode based on the reply instruction responsive to the second instruction.

Optionally, to serve as one embodiment, before the control circuit controls the power adapter to adjust the charging current to the charging current corresponding to the first charging mode, the control circuit further performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine the charging current corresponding to the first charging mode.

Optionally, to serve as one embodiment, when the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine the charging current corresponding to the first charging mode, the control circuit sends a third instruction to the terminal. The third instruction is configured to inquire about a maximum charging current currently supported by the terminal. The control circuit receives a reply instruction responsive to the third instruction sent by the terminal. The reply instruction responsive to the third instruction is configured to indicate the maximum charging current currently supported by the terminal. The control circuit determines a charging current of the first charging mode based on the reply instruction responsive to the third instruction.

The power adapter can directly determine the maximum charging current as the charging current of the fast charge mode, or set the charging current as a current value that is less than the maximum charging current.

Optionally, to serve as one embodiment, during the process that the power adapter is operable in the first charging mode to charge the terminal, the control circuit further performs the bidirectional communication with the terminal through the data lines in the first charging interface to continuously adjust the charging current output to the battery from the power adapter through controlling the switch circuit.

The power adapter can continuously inquire about current state information of the terminal, for example, inquire about the battery voltage, the battery power level, etc., so as to continuously adjust the charging current output to the battery from the power adapter.

Optionally, to serve as one embodiment, when the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface to continuously adjust the charging current output to the battery from the power adapter through controlling the switch circuit, the control circuit sends a fourth instruction to the terminal. The fourth instruction is configured to inquire about a current voltage of the battery in the terminal. The control circuit receives a reply instruction responsive to the fourth instruction sent by the terminal. The reply instruction responsive to the fourth instruction is configured to indicate the current voltage of the battery in the terminal. The control circuit adjusts the charging current output to the battery from the power adapter through controlling the switch circuit based on the current voltage of the battery.

Optionally, to serve as one embodiment, the control circuit adjusts the charging current output to the battery from the power adapter to a charging current value corresponding to the current voltage of the battery through controlling the switch circuit based on the current voltage of the battery and a predetermined relationship between a battery voltage value and a charging current value.

The power adapter can store the relationship between the battery voltage value and the charging current value in advance. The power adapter can perform the bidirectional communication with the terminal through the data lines in the first charging interface to obtain the relationship between the battery voltage value and the charging current value stored in the terminal from a terminal side.

Optionally, to serve as one embodiment, during the process that the power adapter is operable in the first charging mode to charge the terminal, the control circuit further performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine whether there is a bad contact between the first charging interface and the second charging interface or not. When it is determined that there is a bad contact between the first charging interface and the second charging interface, the control circuit controls the power adapter to exit the quick charging mode.

Optionally, to serve as one embodiment, before determining whether there is a bad contact between the first charging interface and the second charging interface or not, the control circuit is further configured to receive information for indicating a path impedance of the terminal from the terminal. The control circuit sends the fourth instruction to the terminal. The fourth instruction is configured to inquire about voltage of the battery in the terminal. The control circuit receives the reply instruction responsive to the fourth instruction sent by the terminal. The reply instruction responsive to the fourth instruction is configured to indicate the voltage of the battery in the terminal. The control circuit determines a path impedance from the power adapter to the battery based on the output voltage of the power adapter and the voltage of the battery. The control circuit determines whether there is a bad contact between the first charging interface and the second charging interface or not based on the path impedance from the power adapter to the battery, the path impedance of the terminal, and a path impedance of the charging lines between the power adapter and the terminal.

The terminal can record the path impedance of the terminal in advance. For example, since terminals of a same model have a same structure, path impedances of the terminals are set as a same value in default setting. Similarly, the power adapter can record the path impedance of the charging lines in advance. When the power adapter obtains voltage across two terminals of the battery of the terminal, a path impedance of an overall path can be determined based on a voltage drop between the power adapter and the two terminals of the battery and a path current. Upon on a condition that the path impedance of the overall path is greater than a sum of the path impedance of the terminal and the path impedance of the charging lines, or the path impedance of the overall path minus a sum of the path impedance of the terminal and the path impedance of the charging lines is greater than a threshold impedance value, it is determined that there is a bad contact between the first charging interface and the second charging interface.

Optionally, to serve as one embodiment, before the power adapter exits the quick charging mode, the control circuit further sends a fifth instruction to the terminal. The fifth instruction is configured to indicate that there is a bad contact between the first charging interface and the second charging interface.

After the power adapter sends the fifth instruction, the power adapter can exit the first charging mode or reset.

In the above, the fast charging process according to the embodiment of the present disclosure is described in detail from the viewpoint of the power adapter, and the fast charging process according to the embodiment of the present disclosure is provided from the viewpoint of the terminal as follows.

Since the interactions between and relevant characteristics, functions, etc. of the power adapter and the terminal described from the terminal side are corresponding to the description from the power adapter side, a repeated description is not provided where appropriate to simplify matters.

According to one embodiment of the present disclosure, as shown in FIG. 13, the terminal 2 further includes a charging control switch 203 and a controller 204. The charging control switch 203, such as a switch circuit constituted by electronic switch elements, is connected between the second charging interface 201 and the battery 202. The charging control switch 203 is configured to enable or end a charging process of the battery 202 under a control of the controller 204, so that the charging process of the battery 202 can be controlled from the terminal side to ensure the safety and reliability of the charging of the battery 202.

As shown in FIG. 14, the terminal 2 further includes a communication circuit 205. The communication circuit 205 is configured to establish a bidirectional communication between the controller 204 and the control circuit 107 through the second charging interface 201 and the first charging interface 105. That is, the terminal 2 and the power adapter 1 can perform the bidirectional communication through the data lines in the USB interface. The terminal 2 supports the second charging mode and the first charging mode. A charging current of the first charging mode is greater than a charging current of the second charging mode. The communication circuit 205 and the control circuit 107 perform a bidirectional communication to allow the power adapter 1 to determine using the first charging mode to charge the terminal 2, so that the control circuit 107 controls the power adapter 1 to output the charging current corresponding to the first charging mode to charge the battery 202 in the terminal 2.

According to the embodiment of the present disclosure, the power adapter 1 does not blindly increase the output current to perform fast charging. Rather, the power adapter 1 needs to perform the bidirectional communication with the terminal 2 so as to negotiate whether the first charging mode can be used or not. As compared with the prior art, the safety of fast charging process is improved.

Optionally, to serve as one embodiment, the controller receives a first instruction sent by the control circuit through the communication circuit. The first instruction is configured to inquire of the terminal whether to enable the first charging mode or not. The controller sends a reply instruction responsive to the first instruction to the control circuit through the communication circuit. The reply instruction responsive to the first instruction is configured to indicate that the terminal agrees to enable the first charging mode.

Optionally, to serve as one embodiment, before the controller receives the first instruction sent by the control circuit through the communication circuit, the power adapter charges the battery in the terminal through the second charging mode. After the control circuit determines that a charging time of the second charging mode is longer than a predetermined threshold value, the control circuit sends the first instruction to the communication circuit in the terminal. The controller receives the first instruction sent by the control circuit through the communication circuit.

Optionally, to serve as one embodiment, before the power adapter outputs the charging current corresponding to the first charging mode to charge the battery in the terminal, the controller performs the bidirectional communication with the control circuit through the communication circuit to allow the power adapter to determine the charging voltage corresponding to the first charging mode.

Optionally, to serve as one embodiment, the controller receives a second instruction sent by the control circuit. The second instruction is configured to inquire whether or not a current output voltage of the power adapter is suitable as the charging voltage of the first charging mode. The controller sends a reply instruction responsive to the second instruction to the control circuit. The reply instruction responsive to the second instruction is configured to indicate that the current output voltage of the power adapter is suitable, excessively high, or excessively low.

Optionally, to serve as one embodiment, the controller performs the bidirectional communication with the control circuit to allow the power adapter to determine the charging current corresponding to the first charging mode.

The controller receives a third instruction sent by the control circuit. The third instruction is configured to inquire about a maximum charging current currently supported by the terminal. The controller sends a reply instruction responsive to the third instruction to the control circuit. The reply instruction responsive to the third instruction is configured to indicate the maximum charging current currently supported by the battery in the terminal to allow the power adapter to determine the charging current corresponding to the first charging mode based on the maximum charging current.

Optionally, to serve as one embodiment, during the process that the power adapter is operable in the first charging mode to charge the terminal, the controller performs the bidirectional communication with the control circuit to allow the power adapter to continuously adjust the charging current output to the battery from the power adapter.

The controller receives a fourth instruction sent by the control circuit. The fourth instruction is configured to inquire about a current voltage of the battery in the terminal. The controller sends a reply instruction responsive to the fourth instruction to the control circuit. The reply instruction responsive to the fourth instruction is configured to indicate the current voltage of the battery in the terminal to allow the power adapter to continuously adjust the charging current output to the battery from the power adapter based on the current voltage of the battery.

Optionally, to serve as one embodiment, during the process that the power adapter is operable in the first charging mode to charge the terminal, the controller performs the bidirectional communication with the control circuit through the communication circuit to allow the power adapter to determine whether there is a bad contact between the first charging interface and the second charging interface or not.

The controller receives the fourth instruction sent by the control circuit. The fourth instruction is configured to inquire about the current voltage of the battery in the terminal. The controller sends the reply instruction responsive to the fourth instruction to the control circuit. The reply instruction responsive to the fourth instruction is configured to indicate the current voltage of the battery in the terminal to allow the control circuit to determine whether there is a bad contact between the first charging interface and the second charging interface or not based on the output voltage of the power adapter and the current voltage of the battery.

Optionally, to serve as one embodiment, the controller receives a fifth instruction sent by the control circuit. The fifth instruction is configured to indicate that there is a bad contact between the first charging interface and the second charging interface.

In order to enable and use the first charging mode, the power adapter can perform a fast charging communication process with the terminal. Through one or more handshake negotiations, the fast charging of the battery is achieved. A detailed description of the fast charging communication process and various stages of the fast charging process according to the embodiment of the present disclosure is provided as follows with reference to FIG. 6. It should be understood that the communication steps or operations shown in FIG. 6 are merely examples, and the embodiment of the present disclosure may further perform other operations or variations of the various operations in FIG. 6. In addition, the various stages in FIG. 6 may be performed in an order different from that presented in FIG. 6, and it may not be necessary to perform all the operations in FIG. 6. It is noted that the curve in FIG. 6 is a change trend of a peak value or an average value of a charging current, rather than an actual charging current curve.

As shown in FIG. 6, the fast charging process may include five stages.

Stage 1:

After a terminal is connected to a power supply device, the terminal can detect a type of the power supply device through data lines D+, D−. When the power supply device is detected as a power adapter, a current absorbed by the terminal may be greater than a predetermined threshold current value (for example, may be 1A). When the power adapter detects that an output current of the power adapter has been greater than or equal to I2 for a predetermined time (for example, may be a continuous T1 duration), the power adapter regards that the terminal has completed the type identification of the power supply device. The power adapter turns on a handshake communication between the power adapter and the terminal. The power adapter sends an instruction 1 (corresponding to the first instruction as described above) to inquire of the terminal whether to enable the first charging mode or not (or called flash charging).

When the power adapter receives a reply instruction of the terminal indicating that the terminal does not agree to enable the first charging mode, the output current of the power adapter is detected again. When the output current of the power adapter is still greater than or equal to I2 within a predetermined continuous time (for example, may be the continuous T1 duration), a request is sent again to inquire of the terminal whether to enable the first charging mode or not. The above steps of stage 1 are repeated until the terminal responds to agree to enable the first charging mode, or the output current of the power adapter no longer satisfies the condition of being greater than or equal to I2.

The fast charging process is turned on after the terminal agrees to enable the first charging mode. The fast charging communication process enters a stage 2.

Stage 2:

Voltage in a clipped pulsating waveform output from the power adapter may include plural levels. The power adapter sends an instruction 2 (corresponding to the second instruction as described above) to the terminal to inquire of the terminal whether or not an output voltage of the power adapter matches a current voltage of the battery (or whether or not suitable, that is, whether or not suitable as a charging voltage of the first charging mode), that is, whether or not satisfy the charging requirement.

The terminal responds that the output voltage of the power adapter is excessively high or excessively low or matching. If the power adapter receives a feedback of the terminal that the output voltage of the power adapter is excessively high or excessively low, the control circuit adjusts the output voltage of the power adapter by one level through adjusting a duty cycle of a PWM signal, and sends the instruction 2 to the terminal again to re-inquire whether the output voltage of the power adapter matches or not.

The above steps of stage 2 are repeated until the terminal responds to the power adapter that the output voltage of the power adapter is at a matching level, and the fast charging process enters a stage 3.

Stage 3:

After the power adapter receives the feedback replied by the terminal that the output voltage of the power adapter is matching, the power adapter sends an instruction 3 (corresponding to the third instruction as described above) to the terminal to inquire of the terminal a maximum charging current currently supported by the terminal. The terminal responds to the power adapter with the maximum charging current currently supported by the terminal, and the fast charging process enters a stage 4.

Stage 4:

After the power adapter receives a feedback of the maximum charging current currently supported replied by the terminal, the power adapter can dispose an output current reference value of the power adapter. The control circuit 107 adjusts the duty cycle of the PWM signal based the output current reference value so that the output current of the power adapter satisfies the requirement of the charging current of the terminal, that is, enters the constant current stage. Here the constant current stage refers to that a peak value or an average value of the output current of the power adapter basically remains unchanged (that is, a change amplitude of the peak value or the average value of the output current is very small, for example, changes within 5% of the peak value or the average value of the output current). In other words, a peak value of a current in a third pulsating waveform remains constant in every period.

Stage 5:

When entering the constant current stage, the power adapter sends an instruction 4 (corresponding to the fourth instruction as described above) at every interval of time to inquire of the terminal a current voltage. The terminal can feed back the current voltage of the battery of the terminal to the power adapter. The power adapter can determine whether a USB contact, that is, a contact between a first charging interface and a second charging interface is good or not and whether it is necessary to reduce a current charging current value of the terminal or not based on a feedback of the current voltage of the battery of the terminal replied by the terminal. When the power adapter determines that the USB contact is bad, the power adapter sends an instruction 5 (corresponding to the fifth instruction as described above) and then resets to enter stage 1.

Optionally, in some embodiments, when the terminal responds to the instruction 1 in stage 1, data corresponding to the instruction 1 can attach data (or information) of a path impedance of the terminal. Path impedance data of the terminal may be used for determining whether the USB contact is good or not in stage 5.

Optionally, in some embodiments, time from where the terminal agrees to enable the first charging mode to where the power adapter adjusts the voltage to an appropriate value in stage 2 can be controlled within a certain range. If the time exceeds a predetermined range, the terminal can determine that a request is abnormal and resets quickly.

Optionally, in some embodiments, the terminal can give a feedback that the output voltage of the power adapter is suitable/matching to the power adapter when the output voltage of the power adapter is adjusted to ΔV (ΔV is about 200 to 500 mV) higher than the current voltage of the battery in stage 2. When the terminal gives a feedback that the output voltage of the power adapter is not suitable (that is, excessively high or excessively low) to the power adapter, the control circuit 107 adjusts the duty cycle of the PWM signal based on a voltage sampling value to adjust the output voltage of the power adapter.

Optionally, in some embodiments, a speed of adjusting a magnitude of the output current of the power adapter can be controlled within a certain range in stage 4, so as to avoid an abnormal interruption caused by excessively fast adjustment speed.

Optionally, in some embodiments, a change amplitude of the magnitude of the output current of the power adapter can be controlled within 5% in stage 5. That is, the constant current stage is identified.

Optionally, in some embodiments, the power adapter monitors a charging circuit impedance in a real-time manner in stage 5. That is, an overall charging circuit impedance is monitored through measuring the output voltage of the power adapter and the current charging current, and reading a battery voltage of the terminal. When it is detected that the charging circuit impedance is greater than a path impedance of the terminal plus an impedance of fast charging data lines, the USB contact is regarded as bad to perform a fast charging reset.

Optionally, in some embodiments, after the first charging mode enables, a communication time interval between the power adapter and the terminal can be controlled within a certain range to avoid the fast charging reset.

Optionally, in some embodiments, a stop of the first charging mode (or the fast charging process) can be classified into a recoverable stop and an unrecoverable stop.

For example, when the terminal detects that the battery is full or the USB contact is bad, the fast charging is stopped and a reset is performed to enter stage 1. The terminal does not agree to enable the first charging mode. The fast charging communication process does not enter stage 2. At this time, the fast charging process that has been stopped can be an unrecoverable stop.

In addition, for example, when there is an abnormal communication between the terminal and the power adapter, the fast charging is stopped and the reset is performed to enter stage 1. After the requirement of stage 1 is met, the terminal agrees to enable the first charging mode to restore the fast charging process. At this time, the fast charging process that has been stopped can be a recoverable stop.

Additionally, for example, when the terminal detects that the battery is abnormal, the fast charging is stopped and the reset is performed to enter stage 1. After entering stage 1, the terminal does not agree to enable the first charging mode. After the battery returns to normal and satisfies the requirement of stage 1, the terminal agrees to enable the first charging mode to restore the fast charging process. At this time, the fast charging process that has been stopped can be a recoverable stop.

The communication steps or operations shown in FIG. 6 are merely examples. For example, in stage 1, a handshake communication between the terminal and the power adapter may be initiated by the terminal after the terminal is connected to the power adapter. That is, the terminal sends the instruction 1 to inquire of the power adapter whether to enable the first charging mode (or called flash charging) or not. When the terminal receives a replay instruction of the power adapter indicating that the power adapter agrees to enable the first charging mode, the fast charging process is enabled.

The communication steps or operations shown in FIG. 6 are merely examples. For example, a constant voltage charging stage may be further included after stage 5. That is, in stage 5, the terminal can feed back the current voltage of the battery of the terminal to the power adapter. As voltage of the battery of the terminal rises continuously, the charging is changed to the constant voltage charging stage when the current voltage of the battery of the terminal reaches a threshold constant voltage charging voltage value. The control circuit 107 adjusts the duty cycle of the PWM signal based on a voltage reference value (that is, the threshold constant voltage charging voltage value) so that the output voltage of the power adapter satisfies the requirement of the charging voltage of the terminal, that is, the voltage is basically maintained constantly without change. In the constant voltage charging stage, the charging current gradually decreases. When the current drops to a certain threshold value, the charging is stopped. At this time, the battery is identified as being fully charged. Here the constant voltage charging refers to that a peak voltage of the third pulsating waveform is basically maintained constantly.

According to the embodiment of the present disclosure, obtaining the output voltage of the power adapter refers to obtaining the peak voltage or an average voltage value of the third pulsating waveform. Obtaining the output current of the power adapter refers to obtaining a peak current or an average current value of the third pulsating waveform.

According to one embodiment of the present disclosure, as shown in FIG. 7A, the power adapter 1 further includes: a controllable switch 108 and a filter circuit 109 connected in series. The serially connected controllable switch 108 and filter circuit 109 are connected to a first output terminal of the second rectifying circuit 104. The control circuit 107 is further configured to control the controllable switch 108 to close when a charging mode is determined to be the second charging mode, and control the controllable switch 108 to open when the charging mode is determined to be a first charging mode. In addition, one or more small capacitors are further connected in parallel at an output terminal of the second rectifying circuit 104. Not only can the noise be reduced, but the occurrence of surge phenomenon is also reduced. Or, the output terminal of the second rectifying circuit 104 may further be connected to an LC filter circuit or a π filter circuit to filter the ripple interference. As shown in FIG. 7B, the output terminal of the second rectifying circuit 104 is connected to the LC filter circuit. It is noted that capacitors in the LC filter circuit or the π filter circuit are all small capacitors, which take a very small area.

The filter circuit 109 includes a filter capacitor. The filter capacitor can support 5V standard charging, that is, correspond to the second charging mode. The controllable switch 108 may be constituted by a semiconductor switch device, such as a MOS transistor. When the power adapter uses the second charging mode (or called standard charging) to charge the battery in the terminal, the control circuit 107 controls the controllable switch 108 to close. The filter circuit 109 is connected to the circuit so that an output of the second rectifying circuit can be filtered. In this manner, the power adapter can be better compatible with the DC charging technology. That is, a DC power is applied to the battery of the terminal to achieve DC charging of the battery. For example, under normal circumstances, a filter circuit including an electrolytic capacitor and an ordinary capacitor connected in parallel would support a small capacitor required by 5V standard charging (such as a solid state capacitor). Since the electrolytic capacitor occupies a larger volume, the electrolytic capacitor in the power adapter can be removed to retain a capacitor having a smaller capacitance so as to reduce the size of the power adapter. When the second charging mode is used, a branch where the small capacitor is located can be controlled to conduct. The current is thus filtered to achieve a stable low-power output so that the DC charging of the battery is performed. When the first charging mode is used, the branch where the small capacitor is located can be controlled to disconnect. The output of the second rectifying circuit 104 is not filtered. Voltage/current with a pulsating waveform is directly output to be applied to the battery, thus achieving fast charging of the battery.

With the sampling of an output current of the second rectifying circuit 104, the first current sampling circuit 1061 can individually sample two currents flowing through two current sensing resistors, i.e. a first resistor R1 and a second resistor R2 as illustrated in FIG. 2B, in another embodiment of the present disclosure. The mode switch unit 115 is configured to switch the first current sampling circuit 1061 to operate in a first current sampling mode or a second current sampling mode.

The control circuit 107 is configured to control the mode switch circuit 115 to control the first current sampling circuit 1061 operable in the first current sampling mode, when the control circuit 107 performs a bidirectional communication with the terminal through the data line of the first charging interface to determine that the terminal is charged by the first charging mode. The control circuit 107 is further configured to control the mode switch circuit 115 to control the first current sampling circuit 1061 operable in the second current sampling mode, when the control circuit 107 performs a bidirectional communication with the terminal through the data line of the first charging interface to determine that the terminal is charged by the second charging mode.

Specifically, as FIG. 2B illustrates, the first current sampling circuit 1061 includes a first resistor R1, a second resistor R2, and a current sensor 10611 in another embodiment of the present disclosure. A first end of the first resistor R1 is coupled to an output end of the second rectifying circuit 104. A first end of the second resistor R2 is coupled to the output end of the second rectifying circuit 104. A third resistor R3 is coupled between the first end of the second resistor R2 and the first end of the first resistor R1. A fourth resistor R4 is coupled between a second end of the second resistor R2 and a second end of the first resistor R1. A resistance of the second resistor R2 is greater than a resistance of the first resistor R1, that is the second resistor R2 is a large resistor while the first resistor R1 is a small resistor. The current sensor 10611 is configured to sample the current outputted by the second rectifying circuit 104 according to voltage across the first resistor R1 or voltage across the second resistor R2. The current sensor 10611 can include an operational amplifier.

As FIG. 2B illustrates, the first current sampling circuit 1061 further includes a fifth resistor R5, a sixth resistor R6, a first filter capacitor C11, and a second filter capacitor C12.A first end of the fifth resistor R5 is coupled to the second end of the second resistor R2, and a second end of the fifth resistor R5 is coupled to the current sensor 10611. A first end of the sixth resistor R6 is coupled to the second end of the second resistor R2, and a second end of the sixth resistor R6 is coupled to the current sensor 10611. A first end of the first filter capacitor C11 is coupled to the second end of the fifth resistor R5 and the current sensor 10611. A second end of the first filter capacitor C11 is grounded. A first end of the second filter capacitor C12 is coupled to the second end of the sixth resistor R6 and the current sensor 10611, and a second end of the second filter capacitor C12 is grounded.

In other words, the first current sampling circuit 1061 can detect current through the first resistor R1 (a small resistor) and the second resistor R2 (a large resistor) individually so the first current sampling circuit 1061 can be selectively operable in two current sampling modes.

In another embodiment of the present disclosure, the mode switch circuit 115 includes a first switch SW1 and a second switch SW2, as FIG. 2B illustrates. A first end of the first switch SW1 is coupled to the second end of the first resistor R1, and a control end of the first switch SW1 is coupled to the control circuit 107. A first end of the second switch SW2 is coupled to the second end of the second resistor R2, a control end of the second switch SW2 is coupled to the control circuit 107, and a second end of the second switch SW2 is coupled to a second end of the first switch SW1. Both of the first switch SW1 and the second resistor R2 may be Metal oxide semiconductor (MOS) transistors.

In this embodiment of the present disclosure, when the control circuit 107 performs a bidirectional communication with the terminal through the data line of the first charging interface to determine that the terminal is charged by the first charging mode, i.e. a fast charging with high current, the first current sampling circuit 1061 is operable in the first current sampling mode that current flowing through the small resistor R1 is sensed, as the first switch SW1 turns on and the second switch SW2 turns off. When the control circuit 107 performs a bidirectional communication with the terminal through the data line of the first charging interface to determine that the terminal is charged by the second charging mode, i.e. a standard charging with low current, the first current sampling circuit 1061 is operable in the second current sampling mode that current flowing through the large resistor R2 is sensed, as the first switch SW1 turns off and the second switch SW2 turns on.

Accordingly, by using the charging system for the terminal according to the present disclosure, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

According to one embodiment of the present disclosure, the control circuit 107 is further configured to obtain a charging current and/or a charging voltage corresponding to the first charging mode based on state information of the terminal when the charging mode is determined to be the first charging mode, and modulate a duty cycle of a PWM signal based on the charging current and/or the charging voltage corresponding to the first charging mode. That is, when a current charging mode is determined to be the first charging mode, the control circuit 107 obtains the charging current and/or the charging voltage corresponding to the first charging mode based on acquired state information of the terminal, such as a battery voltage, a battery level, a battery temperature, operating parameters of the terminal, and power consumption information of an application running on the terminal, etc., then modulates the duty cycle of a control signal based on the obtained charging current and/or charging voltage. As a result, an output of the power adapter satisfies the charging requirement to achieve the fast charging of the battery.

The state information of the terminal includes the battery temperature. Additionally, when the battery temperature is higher than a first predetermined threshold temperature or lower than a second predetermined threshold temperature, the first charging mode is switched to the second charging mode if the current charging mode is the first charging mode. The first predetermined threshold temperature is higher the second predetermined threshold temperature. In other words, when the battery temperature is excessively low (for example, the battery temperature lower than the second predetermined threshold temperature) or excessively high (for example, the battery temperature higher than the first predetermined threshold temperature), neither is suitable for fast charging. Therefore, the first charging mode needs to be switched to the second charging mode. According to one embodiment of the present disclosure, the first predetermined threshold temperature and the second predetermined threshold temperature may be set or written to a memory of the control circuit (such as an MCU of the power adapter) depending on practical situations.

In one embodiment of the present disclosure, the control circuit 107 is further configured to control the switch circuit 102 to turn off when the battery temperature is higher than a high temperature protection threshold that is predetermined. That is, the control circuit 107 needs to adopt a high temperature protection strategy to control the switch circuit 102 to turn off when the battery temperature exceeds the high temperature protection threshold, so that the power adapter stops charging the battery. The high temperature protection of battery is thus achieved to improve charging safety. The high temperature protection threshold may be different from the first predetermined threshold temperature, or may be the same as the first predetermined threshold temperature. In at least one embodiment, the high temperature protection threshold is higher than the first predetermined threshold temperature.

In another embodiment of the present disclosure, a controller is further configured to acquired the battery temperature, and control a charging control switch to turn off when the battery temperature is higher than the high temperature protection threshold that is predetermined. That is, the charging control switch is turned off through a terminal side to turn off the charging process of the battery so as to ensure charging safety.

In one embodiment of the present disclosure, the control circuit is further configured to acquire a temperature of the first charging interface, and control the switch circuit to turn off when the temperature of the first charging interface is higher than a predetermined protection temperature. That is, the control circuit 107 also needs to execute the high temperature protection strategy to control the switch circuit 102 to turn off when the temperature of the first charging interface exceeds a certain temperature, so that the power adapter stops charging the battery. The high temperature protection of charging interface is thus achieved to improve the charging safety.

In another embodiment of the present disclosure, the controller acquires the temperature of the first charging interface through performing a bidirectional communication with the control circuit, and controls the charging control switch (see FIG. 13 and FIG. 14) to turn off when the temperature of the first charging interface is higher than the predetermined protection temperature. That is, the charging control switch is turned off through the terminal side to turn off the charging process of the battery so as to ensure charging safety.

In greater detail, in one embodiment of the present disclosure, the power adapter 1 further includes a drive circuit 110, such as a MOSFET driver, as shown in FIG. 8. The drive circuit 110 is connected between the switch circuit 102 and the control circuit 107. The drive circuit 110 is configured to drive the switch circuit 102 to turn on or turn off based on a control signal. Of course, it is noted that the drive circuit 110 may be integrated in the control circuit 107 according to other embodiments of the present disclosure.

As shown in FIG. 8, the power adapter 1 further includes an isolation circuit 111. The isolation circuit 111 is connected between the drive circuit 110 and the control circuit 107 to achieve signal isolation between a primary side and a secondary side of the power adapter 1 (or signal isolation between a primary winding and a secondary winding of the transformer 103). The isolation circuit 111 may use an optocoupler isolation, or may use some other isolation. Through disposing the isolation circuit 111, the control circuit 107 can be disposed on the secondary side of the power adapter 1 (or a secondary winding side of the transformer 103) to facilitate the control circuit 107 to communicate with the terminal 2. As a result, the space design of the power adapter 1 becomes simpler and easier.

In other embodiments of the present disclosure, both the control circuit 107 and the drive circuit 110 can be disposed on the primary side. Under the circumstances, the isolation circuit 111 can be disposed between the control circuit 107 and the sampling circuit 106 to achieve the signal isolation between the primary side and the secondary side of the power adapter 1.

In one embodiment of the present disclosure, the isolation circuit 111 needs to be disposed when the control circuit 107 is disposed on the secondary side. The isolation circuit 111 may be integrated in the control circuit 107. In other words, when a signal is transmitted from the primary side to the secondary side or from the secondary side to the primary side, the isolation circuit usually needs to be disposed to perform signal isolation.

In one embodiment of the present disclosure, as shown in FIG. 9, the power adapter 1 further includes an auxiliary winding and a power supply circuit 112. The auxiliary winding generates voltage in a fourth pulsating waveform based on the voltage with the first pulsating waveform that is modulated. The power supply circuit 112 is connected to the auxiliary winding. The power supply circuit 112 (for example, including a filter regulator module, a voltage conversion module, etc.) is configured to convert the voltage in the fourth pulsating waveform to output DC power so as to supply power to the drive circuit 110 and/or the control circuit 107. The power supply circuit 112 may be constituted by elements, such as a small filter capacitor, a voltage regulator chip, etc., to process and convert the voltage in the fourth pulsating waveform, thus outputting a low voltage DC power, such as 3.3V, or 5V, etc.

In other words, a power supply of the drive circuit 110 can be obtained through converting the voltage in the fourth pulsating waveform by the power supply circuit 112. When the control circuit 107 is disposed on the primary side, a power supply of the control circuit 107 can be obtained through converting the voltage in the fourth pulsating waveform by the power supply circuit 112. As shown in FIG. 9, when the control circuit 107 is disposed on the primary side, the power supply circuit 112 provides a two-way DC output to respectively supply power to the drive circuit 110 and the control circuit 107. The isolation circuit 111, e.g. an optocoupler, is disposed between the control circuit 107 and the sampling circuit 106 to achieve the signal isolation between the primary side and the secondary side of the power adapter 1.

When the control circuit 107 is disposed on the primary side and is integrated with the drive circuit 110, the power supply circuit 112 only supplies power to the control circuit 107. When the control circuit 107 is disposed on the secondary side and the drive circuit 110 is disposed on the primary side, the power supply circuit 112 only supplies power to the drive circuit 110. The power of the control circuit 107 is supplied by the secondary side, for example, a power supply circuit is used to convert the voltage with the third pulsating waveform output from the second rectifying circuit 104 to a DC power so as to supply power to the control circuit 107.

In one embodiment of the present disclosure, output terminals of the first rectifying circuit 101 are further connected in parallel with a plurality of small capacitors to have a filtering effect. Or, the output terminals of the first rectifying circuit 101 are connected to an LC filter circuit.

In another embodiment of the present disclosure, the power adapter 1 further includes a first voltage detection circuit 113 as shown in FIG. 10. The first voltage detection circuit 113 is connected to the auxiliary winding and the control circuit 107. The first voltage detection circuit 113 is configured to detect the voltage in the fourth pulsating waveform to generate a voltage detection value. The control circuit 107 is further configured to modulate a duty cycle of a control signal based on the voltage detection value.

In other words, the control circuit 107 can reflect voltage output from the second rectifying circuit 104 based on voltage output from the auxiliary winding detected by the voltage detection circuit 113, and then modulate the duty cycle of the control signal based on the voltage detection value, so that the output of the second rectifying circuit 104 matches the charging requirement of the battery.

In greater detail, in one embodiment of the present disclosure, the sampling circuit 106 includes a first current sampling circuit 1061 and a first voltage sampling circuit 1062 as shown in FIG. 11. The first current sampling circuit 1061 is configured to sample a current output from the second rectifying circuit 104 to obtain a current sampling value. The voltage sampling circuit 1062 is configured to sample voltage output from the second rectifying circuit 104 to obtain voltage sampling value.

Optionally, the first current sampling circuit 1061 can sample voltage across a resistor (current sensing resistor) connected to the first output terminal of the second rectifying circuit 104 to achieve the sampling of the current output from the second rectifying circuit 104. The first voltage sampling circuit 1062 can sample voltage between the first output terminal and a second output terminal of the second rectifying circuit 104 to achieve the sampling of the voltage output from the second rectifying circuit 104.

In one embodiment of the present disclosure, the first voltage sampling circuit 1062 includes a peak voltage sampling and retaining circuit, a zero-crossing sampling circuit, a discharge circuit, and an analog/digital (AD) sampling circuit as shown in FIG. 11. The peak voltage sampling and retaining circuit is configured to sample and retain a peak voltage of the voltage with the third pulsating waveform. The zero-crossing sampling circuit is configured to sample zero-crossing points of the voltage with the third pulsating waveform. The discharge circuit is configured to discharge the peak voltage sampling and retaining circuit at the zero-crossing points. The AD sampling circuit is configured to sample the peak voltage in the peak voltage sampling and retaining circuit so as to obtain the voltage sampling value.

Through disposing the peak voltage sampling and retaining circuit, the zero-crossing sampling circuit, the discharge circuit, and the AD sampling circuit in the first voltage sampling circuit 1062, accurate sampling of the voltage output from the second rectifying circuit 104 can be achieved. In addition, the voltage sampling value can be ensured to be synchronized with the voltage with the first pulsating waveform, that is, the phases are synchronous and the amplitude change trends are consistent.

According to one embodiment of the present disclosure, the power adapter 1 further includes a second voltage sampling circuit 114 as shown in FIG. 12. The second voltage sampling circuit 114 is configured to sample the voltage with the first pulsating waveform. The second voltage sampling circuit 114 is connected to the control circuit 107. When a voltage value sampled by the second voltage sampling circuit 114 is greater than a first predetermined voltage value, the control circuit 107 controls the switch circuit 102 to turn on for a first predetermined time so as to discharge a surge voltage, a spike voltage, etc. with the first pulsating waveform.

As shown in FIG. 12, the second voltage sampling circuit 114 may be connected to a first output terminal and a second output terminal of the first rectifying circuit 101 to achieve the sampling of the voltage with the first pulsating waveform. The control circuit 107 makes a judgment on the voltage value sampled by the second voltage sampling circuit 114. If the voltage value sampled by the second voltage sampling circuit 114 is greater than the first predetermined voltage value, the power adapter 1 is interfered with by a lighting stroke so the surge voltage appears. At This time, the surge voltage needs to be discharged to ensure the safety and reliability of charging. The control circuit 107 controls the switch circuit 102 to turn on for a period of time to form a discharge path. The surge voltage caused by the lighting stroke is discharged to prevent interference caused by the lighting stroke when the power adapter charges the terminal. As a result, the safety and reliability of charging the terminal is effectively improved. The first predetermined voltage value may be set depending on practical situations.

In one embodiment of the present disclosure, during the process that the power adapter charges the battery 202 of the terminal 2, the control circuit 107 is further configured to control the switch circuit 102 to turn off when a voltage value sampled by the sampling circuit 106 is greater than a second predetermined voltage value. That is, the control circuit 107 further makes a judgment on a magnitude of the voltage value sampled by the sampling circuit 106. If the voltage value sampled by the sampling circuit 106 is greater than a second predetermined voltage value, voltage output from the power adapter 1 is excessively high. At this time, the control circuit 107 controls the switch circuit 102 to turn off so that the power adapter 1 stops charging the battery 202 of the terminal 2. In other words, the control circuit 107 achieves the overvoltage protection of the power adapter 1 through controlling the switch circuit 102 to turn off so as to ensure safe charging.

In one embodiment of the present disclosure, the controller 204 performs the bidirectional communication with the control circuit 107 to acquire the voltage value sampled by the sampling circuit 106 (see FIG. 13 and FIG. 14), and controls the charging control switch 203 to turn off when the voltage value sampled by the sampling circuit 106 is greater than the second predetermined voltage value. That is, the charging control switch 203 is turned off through a side of the terminal 2 so as to turn off the charging process of the battery 202. The charging safety is ensured.

In addition, the control circuit 107 is further configured to control the switch circuit 102 to turn off when a current value sampled by the sampling circuit 106 is greater than a predetermined current value. That is, the control circuit 107 further makes a judgment on a magnitude of the current value sampled by the sampling circuit 106. If the current value sampled by the sampling circuit 106 is greater than the predetermined current value, a current output from the power adapter 1 is excessively high. At this time, the control circuit 107 controls the switch circuit 102 to turn off so that the power adapter 1 stops charging the terminal 2. In other words, the control circuit 107 achieves the overcurrent protection of the power adapter 1 through controlling the switch circuit 102 to turn off so as to ensure safe charging.

Similarly, the controller 204 performs the bidirectional communication with the control circuit 107 to acquire the current value sampled by the sampling circuit 106 (see FIG. 13 and FIG. 14), and controls the charging control switch 203 to turn off when the current value sampled by the sampling circuit 106 is greater than the predetermined current value. That is, the charging control switch 203 is turned off through the side of the terminal 2 so as to turn off the charging process of the battery 202. The charging safety is ensured.

Both the second predetermined voltage value and the predetermined current value may be set or written to a memory of the control circuit (for example, in the control circuit 107 of the power adapter 1, such as a micro controller unit (MCU)) depending on practical situations.

In one embodiment of the present disclosure, the terminal may be a mobile terminal, such as a cellphone, a mobile power supply, such as a charging bank, a multimedia player, a notebook computer, or a wearable device, etc.

According to the embodiment of the present disclosure, the charging system for the terminal controls the power adapter to output the voltage with the third pulsating waveform, and directly applies the voltage with the third pulsating waveform output from the power adapter to the battery in the terminal, so that the fast charging of the battery directly by the output voltage/current that is pulsating can be achieved. A magnitude of the output voltage/current that is pulsating changes periodically. As compared with the disclosures of charging with constant voltage and constant current in the related art, the lithium precipitation phenomenon of the lithium battery can be reduced. The service life of the battery can be improved. In addition, the probability of arcing and the force of the contact at the charging interface can further be reduced to improve the life of the charging interface. It is also advantageous in reducing the polarization effect of the battery, improving the charging speed, reducing the battery heat so as to ensure the safety and reliability when the terminal is charged. Additionally, because the power adapter outputs the voltage with the pulsating waveform, there is no necessity to dispose electrolytic capacitors in the power supply adapter. Not only can the power adapter simplified and miniaturized, but the cost can also be greatly reduced. Additionally, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

In addition, the present disclosure also provides a power adapter. The power adapter includes a first rectifying circuit configured to rectify an alternating current to voltage with a first pulsating waveform, a switch circuit configured to modulate the voltage with the first pulsating waveform according to a control signal, a transformer configured to output voltage with a second pulsating waveform according to the modulated voltage with the first pulsating waveform, a second rectifying circuit configured to rectify the voltage with the second pulsating waveform to voltage in a third pulsating waveform, a first charging interface coupled to the second rectifying circuit, a first current sampling circuit configured to sample current outputted by the second rectifying circuit to obtain a current sampling value, the first current sampling circuit selectively operable in a first current sampling mode and a second current sampling mode, a mode switch circuit configured to control the first current sampling circuit to switch between the first current sampling mode and the second current sampling mode, and a control circuit coupled to the first current sampling circuit, the mode switch circuit, and the mode switch circuit. The control circuit is configured to output the control signal to the switch circuit, configured to control the mode switch circuit to control the first current sampling circuit operating in the first current sampling mode or the second current sampling mode based on a charging mode, and configured to regulate a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of charging. The first charging interface is configured to apply the voltage with the third pulsating waveform to a battery of a terminal through a second charging interface of the terminal when the second charging interface of the terminal couples to the first charging interface. The battery is coupled to the second charging interface.

According to the embodiment of the present disclosure, the power adapter outputs the voltage with the third pulsating waveform through the first charging interface, and directly applies the voltage with the third pulsating waveform output from the power adapter to the battery through the second charging interface in the terminal, so that the fast charging of the battery directly by the output voltage/current that is pulsating can be achieved. A magnitude of the output voltage/current that is pulsating changes periodically. As compared with the disclosures of charging with constant voltage and constant current in the related art, the lithium precipitation phenomenon of the lithium battery can be reduced. The service life of the battery can be improved. In addition, the probability of arcing and the force of the contact at the charging interface can further be reduced to improve the life of the charging interface. It is also advantageous in reducing the polarization effect of the battery, improving the charging speed, reducing the battery heat so as to ensure the safety and reliability when the terminal is charged. Additionally, because the power adapter outputs the voltage with the pulsating waveform, there is no necessity to dispose electrolytic capacitors in the power supply adapter. Not only can the power adapter simplified and miniaturized, but the cost can also be greatly reduced. Additionally, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

FIG. 15 illustrates a flowchart of a charging method for a terminal according to one embodiment of the present disclosure. As shown in FIG. 15, the charging method for the terminal can begin at block S1.

At block S1, an AC power input to a power adapter is rectified for the first time to output voltage with a first pulsating waveform when a first charging interface of the power adapter is connected to a second charging interface of a terminal.

That is, a first rectifying circuit in the power adapter is used to rectify AC mains of an input AC power (that is, mains, such as 220V, 50 Hz or 60 Hz) and output voltage in a clipped pulsating waveform of the voltage with the first pulsating waveform (such as 100 Hz or 120 Hz).

At block S2, a switch circuit is controlled to modulate the voltage with the first pulsating waveform, and voltage with a second pulsating waveform is output through transformation of a transformer.

The switch circuit may be constituted by a MOS transistor. A peak clipping modulation is performed to the voltage in the clipped pulsating waveform through performing a PWM control to the MOS transistor. Then, the voltage with the first pulsating waveform thus modulated is coupled to a secondary side by the transformer, and the voltage with the second pulsating waveform is output by a secondary winding.

In one embodiment of the present disclosure, a high-frequency transformer may be adopted to perform transformation. In this manner, a size of the transformer can be very small, thus being able to achieve a high-power and small-sized design of the power adapter.

At block S3, the voltage with the second pulsating waveform is rectified for the second time to output voltage in a third pulsating waveform. The voltage with the third pulsating waveform can be applied to a battery of the terminal through the second charging interface to achieve the charging of the battery of the terminal.

In one embodiment of the present disclosure, the voltage with the second pulsating waveform is rectified for the second time through a second rectifying circuit. The second rectifying circuit may be constituted by a diode or a MOS transistor to achieve secondary synchronous rectification so that the modulated first pulsating waveform is synchronized with the third pulsating waveform.

At block S4, current corresponding to the voltage with the third pulsating waveform is sampled to obtain a current sampling value. The first current sampling circuit is selectively operable in a first current sampling mode and a second current sampling mode.

At block S5, the first current sampling circuit is controlled to operate in the first current sampling mode or the second current sampling mode according to a charging mode, while a duty cycle of the control signal applied to the switch circuit is modulated based on the current sampling value so that the voltage with the third pulsating waveform satisfies the charging requirement.

According to another embodiment of the present disclosure, a frequency of the control signal is regulated according to the current sampling value.

According to another embodiment of the present disclosure, voltage and/or current being rectified twice can be sampled to obtain a voltage sampling value and/or a current sampling value. A duty cycle of the control signal applied to the switch circuit can be modulated based on the voltage sampling value and/or the current sampling value so that the voltage with the third pulsating waveform satisfies the charging requirement.

It is noted that the voltage with the third pulsating waveform satisfying the charging requirement refers to that the voltage and a current with the third pulsating waveform satisfy a charging voltage and a charging current when the battery is charged. That is, the duty cycle of the control signal, such as a PWM signal, can be modulated based on voltage and/or current output from the power adapter thus sampled to adjust an output of the power adapter in a real-time manner. A closed-loop regulation control is thus realized so that the voltage in the third pulsation waveform satisfies the charging requirement of the terminal to ensure that the battery is safely and reliably charged. The charging voltage waveform output to the battery being regulated through the duty cycle of the PWM signal is shown in FIG. 3. The charging current waveform output to the battery being regulated through the duty cycle of the PWM signal is shown in FIG. 4.

Hence, according to the embodiment of the present disclosure, the voltage in the first pulsation waveform, that is, the voltage in the clipped pulsating waveform, which is rectified by a full bridge is directly modulated by performing PWM peak clipping through controlling the switch circuit, and delivered to the high-frequency transformer to be coupled from a primary side to the secondary side through the high-frequency transformer, and then be recovered as the voltage/current in the clipped pulsating waveform through synchronous rectification to be directly delivered to the battery of the terminal so as to achieve the fast charging of the battery. An amplitude of the voltage in the clipped pulsating waveform can be regulated through adjusting the duty cycle of the PWM signal. As a result, the output of the power adapter satisfies the charging requirement of the battery. It can be seen that the electrolytic capacitors on the primary side and the secondary side in the power adapter can be removed. Through using the voltage in the clipped pulsating waveform to directly charge the battery, the size of the power adapter can be reduced to miniaturize the power adapter and significantly reduce the cost.

According to one embodiment of the present disclosure, the first current sampling circuit is controlled to operate in the first current sampling mode, when a bidirectional communication between the terminal and the power adapter via the first charging interface is established to determine that the terminal is charged by the first charging mode. The first current sampling circuit is controlled to operate in the second current sampling mode, when the bidirectional communication between the terminal and the power adapter via the first charging interface is established to determine that the terminal is charged by the second charging mode.

According to one embodiment of the present disclosure, a frequency of the control signal is modulated based on the voltage sampling value and/or the current sampling value. The PWM signal output to the switch circuit can thus be controlled to be continuously output for a period of time and then be stopped. After the output has been stopped for a predetermined time, the output of the PWM is turned on again. In this manner, the voltage applied to the battery is intermittent and the battery is intermittently charged. As a result, the security worry caused by serious heating when the battery is continuously charged can be avoided to improve the reliability and safety of battery charging. The control signal output to the switch circuit may be shown in FIG. 5.

In addition to that, the charging method for the terminal further includes: state information of the terminal is acquired through a communication between the first charging interface and the terminal so as to modulate the duty cycle of the control signal based on the state information of the terminal, and/or the voltage sampling value and/or the current sampling value.

In other words, when the second charging interface is connected to the first charging interface, the power adapter and the terminal can send a communication inquiry instruction to each other, and establish a communication connection between the power adapter and the terminal after receiving a reply instruction correspondingly. In this manner, the state information of the terminal can be acquired so that the power adapter negotiates a charging mode and charging parameters (such as the charging current, the charging voltage) with the terminal and controls the charging process.

According to one embodiment of the present disclosure, voltage in a fourth pulsating waveform is generated through transformation of the transformer, and the voltage in the fourth pulsating waveform is detected to generate a voltage detection value so as to modulate the duty cycle of the control signal based on the voltage detection value.

In greater detail, an auxiliary winding may be further disposed in the transformer. The auxiliary winding can generate the voltage in the fourth pulsating waveform based on the modulated first pulsating waveform. In this manner, an output voltage of the power adapter can be reflected through detecting the voltage in the fourth pulsating waveform so as to modulate the duty cycle of the control signal based on the voltage detection value. As a result, the output of the power adapter matches the charging requirement of the battery.

In one embodiment of the present disclosure, sampling the voltage that has been rectified twice to obtain the voltage sampling value includes: a peak voltage of the voltage that has been rectified twice is sampled and retained and zero-crossing points of the voltage that has been rectified twice are sampled; a peak voltage sampling and retaining circuit that samples and retains the peak voltage is discharged at the zero-crossing points; the peak voltage in the peak voltage sampling and retaining circuit is sampled to obtained the voltage sampling value. Hence, accurate sampling of the voltage output from the power adapter can be achieved. In addition, the voltage sampling value can be ensured to be synchronized with the voltage with the first pulsating waveform, that is, the phases the amplitude change trends are consistent.

Moreover, in one embodiment of the present disclosure, the charging method for the terminal further includes: the voltage with the first pulsating waveform is sampled and the switch circuit is controlled to turned on for a first predetermined time to discharge a surge voltage with the first pulsating waveform when a voltage value thus sampled is greater than a first predetermined voltage value.

Through sampling the voltage with the first pulsating waveform and then making a judgment on a sampled voltage value, the power adapter is interfered with by a lighting stroke so the surge voltage appears if the sampled voltage value is greater than the first predetermined voltage value. At this time, the surge voltage needs to be discharged to ensure the safety and reliability of charging. The switch circuit needs to be controlled to turn on for a period of time to form a discharge path. The surge voltage caused by the lighting stroke is discharged to prevent interference caused by the lighting stroke when the power adapter charges the terminal. As a result, the safety and reliability of charging the terminal is effectively improved. The first predetermined voltage value may be set depending on practical situations.

According to one embodiment of the present disclosure, the charging mode is further determined through a communication between the first charging interface and the terminal, and a charging current and/or a charging voltage corresponding to a first charging mode is obtained based on the state information of the terminal when the charging mode is determined to be the first charging mode. The duty cycle of the control signal is thus modulated based on the charging current and/or the charging voltage corresponding to the first charging mode. The charging mode includes the first charging mode and a second charging mode.

In other words, when a current charging mode is determined to be the first charging mode, the charging current and/or the charging voltage corresponding to the first charging mode can he obtained based on acquired state information of the terminal, such as a battery voltage, a battery level, a battery temperature, operating parameters of the terminal, and power consumption information of an application running on the terminal, etc. Then, the duty cycle of the control signal is modulated based on the obtained charging current and/or charging voltage. As a result, the output of the power adapter satisfies the charging requirement to achieve the fast charging of the battery.

The state information of the terminal includes the battery temperature. In addition, when the battery temperature is higher than a first predetermined threshold temperature or lower than a second predetermined threshold temperature, the first charging mode is switched to the second charging mode if the current charging mode is the first charging mode. The first predetermined threshold temperature is higher the second predetermined threshold temperature. In other words, when the battery temperature is excessively low (for example, the battery temperature is lower than the second predetermined threshold temperature) or excessively high (for example, the battery temperature is higher than the first predetermined threshold temperature), neither is suitable for fast charging. Therefore, the first charging mode needs to be switched to the second charging mode. In the embodiment of the present disclosure, the first predetermined threshold temperature and the second predetermined threshold temperature may be set depending on practical situations.

In one embodiment of the present disclosure, the switch circuit is controlled to turn off when the battery temperature is higher than a high temperature protection threshold that is predetermined. That is, a high temperature protection strategy needs to be adopted to control the switch circuit to turn off when the battery temperature exceeds the high temperature protection threshold, so that the power adapter stops charging the battery. The high temperature protection of battery is thus achieved to improve charging safety. The high temperature protection threshold may be different from the first predetermined threshold temperature, or may be the same as the first predetermined threshold temperature. In at least one embodiment, the high temperature protection threshold is higher than the first predetermined threshold temperature.

In another embodiment of the present disclosure, the terminal further acquires the battery temperature, and controls the battery by stopping the charging when the battery temperature is higher than the high temperature protection threshold that is predetermined. That is, a charging control switch can be turned off through a terminal side to end the charging process of the battery so as to ensure charging safety.

In one embodiment of the present disclosure, the charging method for the terminal further includes: a temperature of the first charging interface is acquired, and the switch circuit is controlled to turned off when the temperature of the first charging interface is higher than a predetermined protection temperature. That is, the control circuit also needs to execute the high temperature protection strategy to control the switch circuit to turn off when the temperature of the first charging interface exceeds a certain temperature, so that the power adapter stops charging the battery. The high temperature protection of charging interface is thus achieved to improve the charging safety.

In another embodiment of the present disclosure, the terminal acquires the temperature of the first charging interface by performing a bidirectional communication with the power adapter through the second charging interface, and controls the battery by stopping the charging when the temperature of the first charging interface is higher than the predetermined protection temperature. That is, the charging control switch can be turned off through the terminal side to end the charging process of the battery so as to ensure charging safety.

During the process that the power adapter charges the terminal, the switch circuit is controlled to turn off when the voltage sampling value is greater than a second predetermined voltage value. That is, during the process that the power adapter charges the terminal, a judgment is further made on a magnitude of the voltage sampling value. If the voltage sampling value is greater than the second predetermined voltage value, the voltage output from the power adapter is excessively high. At this time, the switch circuit is controlled to turn off so that the power adapter stops charging the terminal. In other words, the overvoltage protection of the power adapter is achieved through controlling the switch circuit to turn off so as to ensure safe charging.

In one embodiment of the present disclosure, the terminal acquires the voltage sampling value by performing the bidirectional communication with the power adapter through the second charging interface, and controls the battery by stopping the charging when the voltage sampling value is greater than the second predetermined voltage value. That is, the charging control switch can be turned off through the terminal side so as to end the charging process of the battery. The charging safety is ensured.

In one embodiment of the present disclosure, during the process that the power adapter charges the terminal, the switch circuit is controlled to turn off when the current sampling value is greater than a predetermined current value. That is, during the process that the power adapter charges the terminal, a judgment is further made on a magnitude of the current sampling value. If the current sampling value is greater than the predetermined current value, the current output from the power adapter is excessively high. At this time, the switch circuit is controlled to turn off so that the power adapter stops charging the terminal. In other words, the overcurrent protection of the power adapter is achieved through controlling the switch circuit to turn off so as to ensure safe charging.

Similarly, the terminal acquires the current sampling value by performing the bidirectional communication with the power adapter through the second charging interface, and controls the battery by stopping the charging when the current sampling value is greater than the predetermined current value. That is, the charging control switch can be turned off through the terminal side so as to end the charging process of the battery. The charging safety is ensured.

Both the second predetermined voltage value and the predetermined current value may be set depending on practical situations.

In one embodiment of the present disclosure, the state information of the terminal comprises a battery level, a battery temperature, voltage/current of the terminal, interface information of the terminal, or path impedance information of the terminal.

In greater detail, the power adapter and the terminal are connected through a universal serial bus (USB) interface. The USB interface may be a normal USB interface, or may be a micro USB interface. Data lines in the USB interface are the data lines in the first charging interface and are configured to provide a bidirectional communication between the power adapter and the terminal. The data lines may be a D+ line and/or a D− line in the USB interface, and the bidirectional communication can refer to the information exchange between the power adapter and the terminal.

The power adapter performs the bidirectional communication with the terminal through the data lines in the USB interface to determine that the terminal is charged by the first charging mode.

Optionally, in some embodiments, when a bidirectional communication between the terminal and the first charging interface is established to determine that the terminal is charged by the first charging mode, a first instruction, configured to inquire of the terminal whether to enable the first charging mode or not, is sent to the terminal by the power adapter, and a reply instruction responsive to the first instruction from the terminal, configured to indicate that the terminal agrees to enable the first charging mode, is received by the power adapter.

Optionally, in some embodiments, before sending the first instruction to the terminal, the power adapter charges the terminal through the second charging mode, the first instruction is sent to the terminal if a charging time of the second charging mode is longer than a predetermined threshold value.

It is noted that if a charging time of the second charging mode is longer than a predetermined threshold value, the power adapter determines that the terminal has identified the power adapter and can enable fast charging inquiry.

Optionally, in some embodiments, before a charging current of the power adapter is adjusted to a charging current corresponding to the first charging mode by controlling the switch circuit, and the power adapter uses the charging current corresponding to the first charging mode to charge the terminal, a charging voltage corresponding to the first charging mode is determined through the bidirectional communication between the terminal and the power adapter via the first charging interface. The power adapter is controlled to adjust a charging voltage to the charging voltage corresponding to the first charging mode.

Optionally, in some embodiments, the determining a charging voltage corresponding to the first charging mode through the bidirectional communication between the terminal and the power adapter via the first charging interface includes: a second instruction that is configured to inquire whether or not a current output voltage of the power adapter is suitable as a charging voltage of the first charging mode is sent to the terminal by the power adapter, and a reply instruction responsive to the second instruction sent by the terminal is received by the power adapter. The reply instruction responsive to the second instruction is configured to indicate that the current output voltage of the power adapter is suitable, excessively high, or excessively low. Then the charging voltage of the first charging mode is determined by the power adapter based on the reply instruction responsive to the second instruction.

Optionally, in some embodiments, before the charging current of the power adapter is adjusted to the charging current corresponding to the first charging mode, the charging current corresponding to the first charging mode is determined through the bidirectional communication between the terminal and the power adapter via the first charging interface.

Optionally, in some embodiments, the determining the charging current corresponding to the first charging mode through the bidirectional communication between the terminal and the power adapter via the first charging interface includes: a third instruction to the terminal is sent by the power adapter, a reply instruction responsive to the third instruction sent by the terminal is received by the power adapter, and a charging current of the first charging mode is determined based on the reply instruction responsive to the third instruction. The third instruction is configured to inquire about a maximum charging current currently supported by the terminal. The reply instruction responsive to the third instruction configured to indicate the maximum charging current currently supported by the terminal.

The power adapter can set the maximum charging current as the charging current of the first charging mode, or any charging current less than maximum charging current as the charging current of the first charging mode.

Optionally, in some embodiments, during the process that the power adapter is operable in the first charging mode to charge the terminal, the charging current output to the battery from the power adapter is continuously adjusted by controlling the switch circuit through the bidirectional communication between the terminal and the power adapter via the first charging interface.

The power adapter can continuously inquiry the current state information of the terminal, such as battery voltage or power volume of the battery, so as to continuously adjust the charging current.

Optionally, in some embodiments, the continuously adjusting the charging current output to the battery from the power adapter through controlling the switch circuit through the bidirectional communication between the terminal and the power adapter via the first charging interface, includes: a fourth instruction to the terminal is sent by the power adapter, a reply instruction responsive to the fourth instruction sent from the terminal is received by the power adapter, and the charging current is adjusted through controlling the switch circuit based on the current voltage of the battery. The fourth instruction is configured to inquire about a current voltage of the battery in the terminal. The reply instruction responsive to the fourth instruction configured to indicate the current voltage of the battery in the terminal.

Optionally, in some embodiments, the adjusting the charging current through controlling the switch circuit based on the current voltage of the battery, includes: the charging current output to the battery from the power adapter is adjusted to a charging current value corresponding to the current voltage of the battery through controlling the switch circuit based on the current voltage of the battery and a predetermined relationship between a battery voltage value and a charging current value.

Optionally, the power adapter can store a relationship between the battery voltage and charging current.

Optionally, in some embodiments, during the process that the power adapter is operable in the first charging mode to charge the terminal, it is determined that whether there is a bad contact between the first charging interface and a second charging interface or not, through the bidirectional communication between the terminal and the power adapter via the first charging interface. The power adapter is controlled to exit the first charging mode when it is determined that there is a bad contact between the first charging interface and the second charging interface.

Optionally, in some embodiments, before determining whether there is a bad contact between the first charging interface and the second charging interface or not, an information indicative of a path impedance of the terminal from the terminal is received. The receiving information indicative of a path impedance of the terminal from the terminal includes: a fourth instruction to the terminal is sent by the power adapter, a reply instruction responsive to the fourth instruction sent by the terminal is received by the power adapter, a path impedance from the power adapter to the battery is determined based on an output voltage of the power adapter and the voltage of the battery, and it is determined whether there is a bad contact between the first charging interface and the second charging interface or not based on the path impedance from the power adapter to the battery, the path impedance of the terminal, and a path impedance of charging lines between the power adapter and the terminal. The fourth instruction is configured to inquire about voltage of the battery in the terminal. The reply instruction responsive to the fourth instruction is configured to indicate the voltage of the battery in the terminal.

Optionally, in some embodiments, before the power adapter is controlled to exit the first charging mode, a fifth instruction is sent to the terminal. The fifth instruction is configured to indicate that there is a bad contact between the first charging interface and the second charging interface.

After sending the fifth instruction, the power adapter can exit rapidly and reset.

The description of fast charging process in the above paragraphs is in view of the power adapter. The following describes the fast charging process in view of the terminal.

According to the present disclosure, the terminal supports the second charging mode and the first charging mode. A charging current of the first charging mode is greater than a charging current of the second charging mode. The power adapter determines that the first charging mode is used to charge the terminal, through the bidirectional communication between the second charging interface of the terminal and the adapter. The power adapter outputs the charging current corresponding to the first charging mode to charge the battery in the terminal.

Optionally, in some embodiments, determining that the first charging mode is used to charge the terminal, through the bidirectional communication between the second charging interface of the terminal and the adapter, includes: the terminal receives a first instruction sent from the power adapter, the first instruction configured to inquire of the terminal whether to enable the first charging mode or not; the terminal sends a reply instruction responsive to the first instruction to the power adapter, the reply instruction responsive to the first instruction configured to indicate that the terminal agrees to enable the first charging mode.

Optionally, in some embodiments, before receiving the first instruction sent from the power adapter, the power adapter charges the terminal through the second charging mode. The terminal receives the first instruction sent from the power adapter if a charging time of the second charging mode is longer than a predetermined threshold value.

Optionally, in some embodiments, before a charging current of the power adapter is adjusted to a charging current corresponding to the first charging mode, and the power adapter uses the charging current corresponding to the first charging mode to charge the terminal, the charging voltage corresponding to the first charging mode is determined through the bidirectional communication between the power adapter and the second charging interface of the terminal.

Optionally, in some embodiments, determining the charging voltage corresponding to the first charging mode through the bidirectional communication between the power adapter and the second charging interface of the terminal, includes: the terminal receives a second instruction sent by the power adapter, the second instruction configured to inquire whether or not a current output voltage of the power adapter is suitable as a charging voltage of the first charging mode; the terminal sends a reply instruction responsive to the second instruction to the power adapter, the reply instruction responsive to the second instruction configured to indicate that the current output voltage of the power adapter is suitable, excessively high, or excessively low.

Optionally, in some embodiments, before the charging current of the power adapter is adjusted to the charging current corresponding to the first charging mode, and the terminal uses the charging current corresponding to the first charging mode to charge the battery, the power adapter determines the charging current corresponding to the first charging mode through the bidirectional communication between the power adapter and the second charging interface of the terminal.

Optionally, in some embodiments, the power adapter determines the charging current corresponding to the first charging mode through the bidirectional communication between the power adapter and the second charging interface of the terminal, includes: the terminal receives a third instruction sent by the power adapter, the third instruction configured to inquire about a maximum charging current currently supported by the terminal; the terminal sends a reply instruction responsive to the third instruction to the power adapter, the reply instruction responsive to the third instruction configured to indicate the maximum charging current currently supported by the terminal to allow the power adapter to determine the charging current corresponding to the first charging mode based on the maximum charging current.

Optionally, in some embodiments, during the process that the power adapter is operable in the first charging mode to charge the terminal, the power adapter continuously adjusts the charging current output to the battery from the power adapter through the bidirectional communication between the terminal and the power adapter via the first charging interface.

Optionally, in some embodiments, continuously adjusting the charging current output to the battery from the power adapter through the bidirectional communication between the terminal and the power adapter via the first charging interface, includes: the terminal receives a fourth instruction sent by the power adapter, the fourth instruction configured to inquire about a current voltage of the battery in the terminal; the terminal sends a reply instruction responsive to the fourth instruction to the power adapter, the reply instruction responsive to the fourth instruction configured to indicate the current voltage of the battery in the terminal to allow the power adapter to continuously adjust the charging current output to the battery from the power adapter based on the current voltage of the battery.

Optionally, in some embodiments, during the process that the power adapter is operable in the first charging mode to charge the terminal, the power adapter determines whether there is a bad contact between the first charging interface and the second charging interface or not through the bidirectional communication between the second charging interface and the power adapter.

Optionally, in some embodiments, determining whether there is a bad contact between the first charging interface and the second charging interface or not through the bidirectional communication between the second charging interface and the power adapter, includes: the terminal receives a fourth instruction sent by the power adapter, the fourth instruction configured to inquire about a current voltage of the battery in the terminal; the terminal sends a reply instruction responsive to the fourth instruction to the control circuit, the reply instruction responsive to the fourth instruction configured to indicate the current voltage of the battery in the terminal to allow the power adapter to determine whether there is a bad contact between the first charging interface and the second charging interface or not based on the output voltage of the power adapter and the current voltage of the battery.

Optionally, in some embodiments, the terminal receives a fifth instruction sent by the power adapter. The fifth instruction is configured to indicate that there is a bad contact between the first charging interface and the second charging interface.

In order to enable the first charging mode, the power adapter can perform a fast charging communication process with the terminal. Through one or more handshake negotiations, the fast charging of the battery is achieved. A detailed description of the fast charging communication process and various stages of the fast charging process according to the embodiment of the present disclosure is provided as follows with reference to FIG. 6. It should be understood that the communication steps or operations shown in FIG. 6 are merely examples, and the embodiment of the present disclosure may further perform other operations or variations of the various operations in FIG. 6. In addition, the various stages in FIG. 6 may be performed in an order different from that presented in FIG. 6, and it may not be necessary to perform all the operations in FIG. 6.

In summary, according to the embodiment of the present disclosure, the charging method for the terminal controls the power adapter to output the voltage with the third pulsating waveform that satisfies the charging requirement, and directly applies the voltage with the third pulsating waveform output from the power adapter to the battery in the terminal, so that the fast charging of the battery directly by the output voltage/current that is pulsating can be achieved. A magnitude of the output voltage/current that is pulsating changes periodically. As compared with the disclosure of charging with constant voltage and constant current in the related art, the lithium precipitation phenomenon of the lithium battery can be reduced. The service life of the battery can be improved. In addition, the probability of arcing and the force of the contact at the charging interface can further be reduced to improve the life of the charging interface. It is also advantageous in reducing the polarization effect of the battery, improving the charging speed, reducing the battery heat so as to ensure the safety and reliability when the terminal is charged. Additionally, because the power adapter outputs the voltage with the pulsating waveform, there is no necessity to dispose electrolytic capacitors in the power adapter. Not only can the power adapter be simplified and miniaturized, but the cost can also be greatly reduced. Additionally, two current sampling modes are alternatively switched to sample the current, which ensures the sensing function with the compatibility between sensing precision and dynamic range and expands the scope of the applications.

In the disclosure, it is should be understood that spatially relative terms, such as “center”, “longitudinal”, “lateral”, “length”, “width”, “above”, “below”, “front”, “back”, “left”, “right”, “horizontal”, “vertical”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The spatially relative terms are not limited to specific orientations depicted in the figures.

In addition, the term “first”, “second” are for illustrative purposes only and are not to be construed as indicating or imposing a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature that limited by “first”, “second” may expressly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of “plural” is two or more, unless otherwise specifically defined.

All of the terminologies containing one or more technical or scientific terminologies have the same meanings that persons skilled in the art understand ordinarily unless they are not defined otherwise. For example, “arrange,” “couple,” and “connect,” should be understood generally in the embodiments of the present disclosure. For example, “firmly connect,” “detachably connect,” and “integrally connect” are all possible. It is also possible that “mechanically connect,” “electrically connect,” and “mutually communicate” are used. It is also possible that “directly couple,” “indirectly couple via a medium,” and “two components mutually interact” are used.

All of the terminologies containing one or more technical or scientific terminologies have the same meanings that persons skilled in the art understand ordinarily unless they are not defined otherwise. For example, “upper” or “lower” of a first characteristic and a second characteristic may include a direct touch between the first and second characteristics. The first and second characteristics are not directly touched; instead, the first and second characteristics are touched via other characteristics between the first and second characteristics. Besides, the first characteristic arranged on/above/over the second characteristic implies that the first characteristic arranged right above/obliquely above or merely means that the level of the first characteristic is higher than the level of the second characteristic. The first characteristic arranged under/below/beneath the second characteristic implies that the first characteristic arranged right under/obliquely under or merely means that the level of the first characteristic is lower than the level of the second characteristic.

In the description of this specification, the description of the terms “one embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples”, and the like, means to refer to the specific feature, structure, material or characteristic described in connection with the embodiments or examples being included in at least one embodiment or example of the present disclosure. In the present specification, the term of the above schematic representation is not necessary for the same embodiment or example. Furthermore, the specific feature, structure, material, or characteristic described may be in combination in a suitable manner in any one or more of the embodiments or examples. In addition, it will be apparent to those skilled in the art that different embodiments or examples described in this specification, as well as features of different embodiments or examples, may be combined without contradictory circumstances.

One having ordinary skill in the art may be aware that the units and steps of algorithm in the examples of the embodiments published by this application can be realized by electronic hardware, or combinations of computer software and electronic hardware. Whether the functions should be performed by hardware or software should depend upon the particular applications and design constraints of a technical solution. One skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered as outside of the scope of the present disclosure.

One skilled in the art may clearly understand that they can refer to the corresponding process in the abovementioned embodiments of the method for the specific operating process of the abovementioned system, device, and circuits. No description is provided herein again for the convenience and succinctness of the description.

In the several embodiments provided by the application, it should be understood that the revealed system, device and method may be implemented in other ways. For example, the abovementioned embodiments of the device are merely schematic. For example, the division of the circuits is merely a division based on logical functions; it may be different when they are put into practice. For example, a plurality of circuits or components may be combined or integrated into another system, or some features may be ignored or not be performed. And another point is that the displayed or discussed coupling, direct coupling or communication can be done through some interfaces, devices, or indirect coupling or communication between circuits; they may be electrical, mechanical, or in other forms.

The circuits described as separated parts may or may not be physically separated. A part that appeared as a circuit may or may not be a physical circuit, i.e. it can locate in one place, or it can be distributed to multiple network circuits. Part of or all of the circuits can be selected based on actual needs to achieve the object of the solutions of the present embodiments.

Furthermore, each of the functional circuits in the embodiments of the present disclosure may be integrated in one processing circuit, or may be independent circuits physically separated, or may integrate with another one or more circuits and appear as a single circuit.

If the function is realized as a software functional unit and used or sold as a standalone product, it may be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present disclosure per se, or its contribution to the related art, or the technical solution may be realized in a software product. The computer software product is stored in a storage medium, including several commands that enable a computer device (may be a personal computer, a server, or network device) to perform all or part of the steps of the methods of the various embodiments of the present disclosure. The storage medium includes U-disk, removable hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or compact disc (CD) and other medium that can store program codes.

The above texts are merely specific embodiments of the present disclosure. However, the scope of the present disclosure is not limited hereto. Any variations or alternatives that can easily be thought of by technicians familiar with the field should fall within the scope of the present disclosure. Therefore, the scope of the present disclosure should be defined by the scope of the claims. 

What is claimed is:
 1. A charging system, comprising: a battery; a first rectifying circuit, configured to rectify an alternating current to voltage with a first pulsating waveform; a switch circuit, configured to modulate the voltage with the first pulsating waveform according to a control signal; a transformer, configured to output voltage with a second pulsating waveform according to the modulated voltage with the first pulsating waveform; a second rectifying circuit, configured to rectify the voltage with the second pulsating waveform to voltage with a third pulsating waveform; a first current sampling circuit, configured to sample current outputted by the second rectifying circuit to obtain a current sampling value, the first current sampling circuit selectively operable in a first current sampling mode and a second current sampling mode; a mode switch circuit, configured to control the first current sampling circuit to switch between the first current sampling mode and the second current sampling mode; and a control circuit, coupled to the first current sampling circuit, the mode switch circuit, and the mode switch circuit, the control circuit configured to output the control signal to the switch circuit, configured to control the mode switch circuit to control the first current sampling circuit operating in the first current sampling mode or the second current sampling mode based on a charging mode, and configured to regulate a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of at least one of a charging voltage or a charging current for charging the battery.
 2. A power adapter, comprising: a first rectifying circuit, configured to rectify an alternating current to voltage with a first pulsating waveform; a switch circuit, configured to modulate the voltage with the first pulsating waveform according to a control signal; a transformer, configured to output voltage with a second pulsating waveform according to the modulated voltage with the first pulsating waveform; a second rectifying circuit, configured to rectify the voltage with the second pulsating waveform to voltage with a third pulsating waveform; a first charging interface, coupled to the second rectifying circuit and configured to apply the voltage with the third pulsating waveform to a battery of a terminal through a second charging interface of the terminal when the second charging interface of the terminal couples to the first charging interface, wherein the battery is coupled to the second charging interface; a first current sampling circuit, configured to sample current outputted by the second rectifying circuit to obtain a current sampling value, the first current sampling circuit selectively operable in a first current sampling mode and a second current sampling mode; a mode switch circuit, configured to control the first current sampling circuit to switch between the first current sampling mode and the second current sampling mode; and a control circuit, coupled to the first current sampling circuit, the mode switch circuit, and the switch circuit, the control circuit configured to output the control signal to the switch circuit, configured to control the mode switch circuit to control the first current sampling circuit operating in the first current sampling mode or the second current sampling mode based on a charging mode, and configured to regulate a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of at least one of a charging voltage or a charging current for charging.
 3. The power adapter as claimed in claim 2, wherein the control circuit is further configured to regulate a frequency of the control signal according to the current sampling value.
 4. The power adapter as claimed in claim 2, wherein the charging interface comprises a power line configured to charge the battery and a data line configured to communicate with the terminal; the control circuit communicates with the terminal through the first charging interface to determine the charging mode that comprises a first charging mode and a second charging mode.
 5. The power adapter as claimed in claim 4, wherein the control circuit is further configured to control the mode switch circuit to control the first current sampling circuit operable in the first current sampling mode, when the control circuit performs a bidirectional communication with the terminal through the data line of the first charging interface to determine that the terminal is charged by the first charging mode; and the control circuit is further configured to control the mode switch circuit to control the first current sampling circuit operable in the second current sampling mode, when the control circuit performs a bidirectional communication with the terminal through the data line of the first charging interface to determine that the terminal is charged by the second charging mode.
 6. The power adapter as claimed in claim 2, wherein the first current sampling circuit comprises: a first resistor, a first end of the first resistor coupled to an output end of the second rectifying circuit; a second resistor, a first end of the second resistor coupled to the output end of the second rectifying circuit, wherein a resistance of the second resistor is greater than a resistance of the first resistor; a third resistor, coupled between the first end of the second resistor and the first end of the first resistor; a fourth resistor, coupled between a second end of the second resistor and a second end of the first resistor; and a current sensor, configured to sample the current outputted by the second rectifying circuit according to voltage across the first resistor or voltage across the second resistor.
 7. The power adapter as claimed in claim 6, wherein the first current sampling circuit further comprises: a fifth resistor, a first end of the fifth resistor coupled to the second end of the second resistor and a second end of the fifth resistor coupled to the current sensor; a sixth resistor, a first end of the sixth resistor coupled to the second end of the second resistor, and a second end of the sixth resistor coupled to the current sensor; a first filter capacitor, a first end of the first filter capacitor coupled to the second end of the fifth resistor and the current sensor and a second end of the first filter capacitor being grounded; and a second filter capacitor, a first end of the second filter capacitor coupled to the second end of the sixth resistor and the current sensor, and a second end of the second filter capacitor being grounded.
 8. The power adapter as claimed in claim 6, wherein the mode switch circuit comprises: a first switch, a first end of the first switch coupled to the second end of the first resistor, and a control end of the first switch coupled to the control circuit; a second switch, a first end of the second switch coupled to the second end of the second resistor, a control end of the second switch coupled to the control circuit, and a second end of the second switch coupled to a second end of the first switch.
 9. The power adapter as claimed in claim 4, wherein when the control circuit performs a bidirectional communication with the terminal through the data lines in the first charging interface to determine that the terminal is charged by the first charging mode, the control circuit sends a first instruction to the terminal, the first instruction is configured to inquire of the terminal whether to enable the first charging mode or not; the control circuit receives a reply instruction responsive to the first instruction from the terminal, the reply instruction responsive to the first instruction is configured to indicate that the terminal agrees to enable the first charging mode.
 10. The power adapter as claimed in claim 9, wherein before the control circuit sends the first instruction to the terminal, the power adapter charges the terminal through the second charging mode, and the control circuit sends the first instruction to the terminal after determining that a charging time of the second charging mode is longer than a predetermined threshold value.
 11. The power adapter as claimed in claim 9, wherein the control circuit is further configured to control the power adapter through controlling the switch circuit so as to adjust a charging current to a charging current corresponding to the first charging mode, and before the power adapter uses the charging current corresponding to the first charging mode to charge the terminal, the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine a charging voltage corresponding to the first charging mode and control the power adapter to adjust a charging voltage to the charging voltage corresponding to the first charging mode.
 12. The power adapter as claimed in claim 11, wherein when the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine the charging voltage corresponding to the first charging mode, the control circuit sends a second instruction to the terminal, the second instruction is configured to inquire whether or not a current output voltage of the power adapter is suitable as a charging voltage of the first charging mode; the control circuit receives a reply instruction responsive to the second instruction sent by the terminal, the reply instruction responsive to the second instruction is configured to indicate that the current output voltage of the power adapter is suitable, excessively high, or excessively low; the control circuit determines the charging voltage of the first charging mode based on the reply instruction responsive to the second instruction.
 13. The power adapter as claimed in claim 11, wherein before the control circuit controls the power adapter to adjust the charging current to the charging current corresponding to the first charging mode, the control circuit further performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine the charging current corresponding to the first charging mode.
 14. The power adapter as claimed in claim 13, wherein when the control circuit performs the bidirectional communication with the terminal through the data lines in the first charging interface to determine the charging current corresponding to the first charging mode, the control circuit sends a third instruction to the terminal, the third instruction is configured to inquire about a maximum charging current currently supported by the terminal; the control circuit receives a reply instruction responsive to the third instruction sent by the terminal, the reply instruction responsive to the third instruction is configured to indicate the maximum charging current currently supported by the terminal; the control circuit determines a charging current of the first charging mode based on the reply instruction responsive to the third instruction.
 15. The power adapter as claimed in claim 9, wherein during the process that the power adapter is operable in the first charging mode to charge the terminal, the control circuit further performs the bidirectional communication with the terminal through the data lines in the first charging interface to continuously adjust the charging current output to the battery from the power adapter through controlling the switch circuit.
 16. A charging method of charging a terminal, comprising: rectifying an alternating current to output voltage with a first pulsating waveform when a first charging interface of a power adapter couples a second charging interface of the terminal; modulating, by controlling a mode switch circuit, the voltage with the first pulsating waveform, and converting, by a transformer, the modulated voltage with the first pulsating waveform into voltage with a second pulsating waveform; rectifying the voltage with the second pulsating waveform to output voltage with a third pulsating waveform, and applying the voltage with the third pulsating waveform to a battery of the terminal through the second charging interface; sampling current corresponding to the voltage with the third pulsating waveform to obtain a current sampling value, wherein the first current sampling circuit is selectively operable in a first current sampling mode and a second current sampling mode; and controlling the first current sampling circuit to operate in the first current sampling mode or the second current sampling mode according to a charging mode, and regulating a duty cycle of the control signal according to the current sampling value so that the voltage with the third pulsating waveform satisfies a requirement of at least one of a charging voltage or a charging current for charging.
 17. The charging method as claimed in claim 16, further comprising: regulating a frequency of the control signal according to the current sampling value.
 18. The charging method as claimed in claim 16, further comprising: determining the charging mode by a communication between the first charging interface and the terminal, the charging mode comprising a first charging mode and a second charging mode.
 19. The charging method as claimed in claim 18, further comprising: controlling the first current sampling circuit to operate in the first current sampling mode, when a bidirectional communication between the terminal and the power adapter via the first charging interface is established to determine that the terminal is charged by the first charging mode; and controlling the first current sampling circuit to operate in the second current sampling mode, when the bidirectional communication between the terminal and the power adapter via the first charging interface is established to determine that the terminal is charged by the second charging mode.
 20. The charging method as claimed in claim 18, further comprising: when the bidirectional communication between the terminal and the power adapter via the first charging interface is established to determine that the terminal is charged by the first charging mode, sending, by the power adapter, a first instruction to the terminal, the first instruction configured to inquire of the terminal whether to enable the first charging mode or not; receiving, by the power adapter, a reply instruction responsive to the first instruction from the terminal, the reply instruction responsive to the first instruction configured to indicate that the terminal agrees to enable the first charging mode.
 21. The charging method as claimed in claim 20, wherein before sending the first instruction to the terminal, the power adapter charges the terminal through the second charging mode, and the charging method comprises: sending, by the power adapter, the first instruction to the terminal if a charging time of the second charging mode is longer than a predetermined threshold value.
 22. The charging method as claimed in claim 20, further comprising: determining a charging voltage corresponding to the first charging mode through the bidirectional communication between the terminal and the power adapter via the first charging interface, and controlling the power adapter to adjust a charging voltage to the charging voltage corresponding to the first charging mode; and adjusting a charging current of the power adapter to a charging current corresponding to the first charging mode by controlling a switch circuit, and charging the terminal by the charging current corresponding to the first charging mode outputted by the power adapter.
 23. The charging method as claimed in claim 20, wherein during the process that the power adapter is operable in the first charging mode to charge the terminal, the charging method further comprises: continuously adjusting, by controlling the switch circuit, the charging current output to the battery from the power adapter through the bidirectional communication between the terminal and the power adapter via the first charging interface.
 24. The charging method as claimed in claim 18, wherein the terminal supports the second charging mode and the first charging mode, and a charging current of the first charging mode is greater than a charging current of the second charging mode, wherein the charging method further comprises: determining, by the power adapter, that the first charging mode is used to charge the terminal, through the bidirectional communication between the second charging interface of the terminal and the adapter; outputting, by the power adapter, the charging current corresponding to the first charging mode to charge the battery in the terminal.
 25. The charging method as claimed in claim 24, wherein determining that the first charging mode is used to charge the terminal, through the bidirectional communication between the second charging interface of the terminal and the adapter, comprises: receiving, by the terminal, a first instruction sent from the power adapter, the first instruction configured to inquire of the terminal whether to enable the first charging mode or not; sending, by the terminal, a reply instruction responsive to the first instruction to the power adapter, the reply instruction responsive to the first instruction configured to indicate that the terminal agrees to enable the first charging mode. 